diff --git a/oi/CodeGen.cpp b/oi/CodeGen.cpp
index bef102f..ea8e4e3 100644
--- a/oi/CodeGen.cpp
+++ b/oi/CodeGen.cpp
@@ -1157,9 +1157,9 @@ void CodeGen::transform(TypeGraph& typeGraph) {
 
   // Simplify the type graph first so there is less work for later passes
   pm.addPass(RemoveTopLevelPointer::createPass());
+  pm.addPass(IdentifyContainers::createPass(containerInfos_));
   pm.addPass(Flattener::createPass());
   pm.addPass(AlignmentCalc::createPass());
-  pm.addPass(IdentifyContainers::createPass(containerInfos_));
   pm.addPass(TypeIdentifier::createPass(config_.passThroughTypes));
   if (config_.features[Feature::PruneTypeGraph])
     pm.addPass(Prune::createPass());
@@ -1173,9 +1173,9 @@ void CodeGen::transform(TypeGraph& typeGraph) {
     pm.addPass(AddChildren::createPass(drgnParser, symbols_));
 
     // Re-run passes over newly added children
+    pm.addPass(IdentifyContainers::createPass(containerInfos_));
     pm.addPass(Flattener::createPass());
     pm.addPass(AlignmentCalc::createPass());
-    pm.addPass(IdentifyContainers::createPass(containerInfos_));
     pm.addPass(TypeIdentifier::createPass(config_.passThroughTypes));
     if (config_.features[Feature::PruneTypeGraph])
       pm.addPass(Prune::createPass());
diff --git a/oi/type_graph/AlignmentCalc.cpp b/oi/type_graph/AlignmentCalc.cpp
index 31a7a30..cf23eff 100644
--- a/oi/type_graph/AlignmentCalc.cpp
+++ b/oi/type_graph/AlignmentCalc.cpp
@@ -48,15 +48,7 @@ void AlignmentCalc::accept(Type& type) {
 }
 
 void AlignmentCalc::visit(Class& c) {
-  for (const auto& param : c.templateParams) {
-    accept(param.type());
-  }
-  for (const auto& parent : c.parents) {
-    accept(parent.type());
-  }
-  for (const auto& child : c.children) {
-    accept(child);
-  }
+  RecursiveVisitor::visit(c);
 
   uint64_t alignment = 1;
   for (auto& member : c.members) {
@@ -82,4 +74,12 @@ void AlignmentCalc::visit(Class& c) {
   }
 }
 
+void AlignmentCalc::visit(Container& c) {
+  RecursiveVisitor::visit(c);
+
+  if (c.underlying()) {
+    c.setAlign(c.underlying()->align());
+  }
+}
+
 }  // namespace oi::detail::type_graph
diff --git a/oi/type_graph/AlignmentCalc.h b/oi/type_graph/AlignmentCalc.h
index 4949341..b89f114 100644
--- a/oi/type_graph/AlignmentCalc.h
+++ b/oi/type_graph/AlignmentCalc.h
@@ -41,6 +41,7 @@ class AlignmentCalc final : public RecursiveVisitor {
 
   void accept(Type& type) override;
   void visit(Class& c) override;
+  void visit(Container& c) override;
 
  private:
   std::unordered_set<Type*> visited_;
diff --git a/oi/type_graph/DrgnParser.h b/oi/type_graph/DrgnParser.h
index 5b8fbe3..1d69636 100644
--- a/oi/type_graph/DrgnParser.h
+++ b/oi/type_graph/DrgnParser.h
@@ -81,7 +81,7 @@ class DrgnParser {
   template <typename T, typename... Args>
   T& makeType(struct drgn_type* drgnType, Args&&... args) {
     auto& newType = typeGraph_.makeType<T>(std::forward<Args>(args)...);
-    drgn_types_.insert({drgnType, newType});
+    drgn_types_.insert_or_assign(drgnType, newType);
     return newType;
   }
   bool chasePointer() const;
diff --git a/oi/type_graph/Flattener.cpp b/oi/type_graph/Flattener.cpp
index 57e3748..28a9f32 100644
--- a/oi/type_graph/Flattener.cpp
+++ b/oi/type_graph/Flattener.cpp
@@ -134,8 +134,6 @@ void Flattener::visit(Class& c) {
   //   };
   //    TODO comment about virtual inheritance
 
-  // TODO alignment of parent classes
-
   // Flatten types referenced by template params, parents and members
   for (const auto& param : c.templateParams) {
     accept(param.type());
@@ -207,12 +205,4 @@ void Flattener::visit(Class& c) {
   }
 }
 
-void Flattener::visit(Container& c) {
-  // Containers themselves don't need to be flattened, but their template
-  // parameters might need to be
-  for (const auto& templateParam : c.templateParams) {
-    accept(templateParam.type());
-  }
-}
-
 }  // namespace oi::detail::type_graph
diff --git a/oi/type_graph/Flattener.h b/oi/type_graph/Flattener.h
index 1d46f02..95f78c6 100644
--- a/oi/type_graph/Flattener.h
+++ b/oi/type_graph/Flattener.h
@@ -42,7 +42,6 @@ class Flattener : public RecursiveVisitor {
 
   void accept(Type& type) override;
   void visit(Class& c) override;
-  void visit(Container& c) override;
 
   static const inline std::string ParentPrefix = "__oi_parent";
 
diff --git a/oi/type_graph/IdentifyContainers.cpp b/oi/type_graph/IdentifyContainers.cpp
index 470f2af..1a4f648 100644
--- a/oi/type_graph/IdentifyContainers.cpp
+++ b/oi/type_graph/IdentifyContainers.cpp
@@ -57,11 +57,12 @@ Type& IdentifyContainers::visit(Class& c) {
       continue;
     }
 
-    auto& container = typeGraph_.makeType<Container>(*containerInfo, c.size());
+    auto& container =
+        typeGraph_.makeType<Container>(*containerInfo, c.size(), &c);
     container.templateParams = c.templateParams;
 
     tracker_.set(c, &container);
-    RecursiveMutator::visit(container);
+    visit(container);
     return container;
   }
 
@@ -70,4 +71,15 @@ Type& IdentifyContainers::visit(Class& c) {
   return c;
 }
 
+Type& IdentifyContainers::visit(Container& c) {
+  for (auto& param : c.templateParams) {
+    param.setType(mutate(param.type()));
+  }
+
+  // Do not mutate the underlying class further here as that would result in it
+  // getting replaced with this Container node
+
+  return c;
+}
+
 }  // namespace oi::detail::type_graph
diff --git a/oi/type_graph/IdentifyContainers.h b/oi/type_graph/IdentifyContainers.h
index 2e7c793..cffb170 100644
--- a/oi/type_graph/IdentifyContainers.h
+++ b/oi/type_graph/IdentifyContainers.h
@@ -48,6 +48,7 @@ class IdentifyContainers : public RecursiveMutator {
 
   Type& mutate(Type& type) override;
   Type& visit(Class& c) override;
+  Type& visit(Container& c) override;
 
  private:
   ResultTracker<Type*> tracker_;
diff --git a/oi/type_graph/Printer.cpp b/oi/type_graph/Printer.cpp
index e7d70eb..0dae0ab 100644
--- a/oi/type_graph/Printer.cpp
+++ b/oi/type_graph/Printer.cpp
@@ -85,7 +85,7 @@ void Printer::visit(const Class& c) {
     print_function(function);
   }
   for (auto& child : c.children) {
-    print_child(child);
+    print_type("Child", child);
   }
 }
 
@@ -93,11 +93,14 @@ void Printer::visit(const Container& c) {
   if (prefix(c))
     return;
 
-  out_ << "Container: " << c.name() << " (size: " << c.size() << ")"
-       << std::endl;
+  out_ << "Container: " << c.name() << " (size: " << c.size()
+       << align_str(c.align()) << ")" << std::endl;
   for (const auto& param : c.templateParams) {
     print_param(param);
   }
+  if (c.underlying()) {
+    print_type("Underlying", *c.underlying());
+  }
 }
 
 void Printer::visit(const Primitive& p) {
@@ -240,11 +243,11 @@ void Printer::print_function(const Function& function) {
   depth_--;
 }
 
-void Printer::print_child(const Type& child) {
+void Printer::print_type(std::string_view header, const Type& type) {
   depth_++;
   prefix();
-  out_ << "Child" << std::endl;
-  print(child);
+  out_ << header << std::endl;
+  print(type);
   depth_--;
 }
 
diff --git a/oi/type_graph/Printer.h b/oi/type_graph/Printer.h
index a66581e..8d7138a 100644
--- a/oi/type_graph/Printer.h
+++ b/oi/type_graph/Printer.h
@@ -51,7 +51,7 @@ class Printer : public ConstVisitor {
   void print_parent(const Parent& parent);
   void print_member(const Member& member);
   void print_function(const Function& function);
-  void print_child(const Type& child);
+  void print_type(std::string_view header, const Type& type);
   void print_value(const std::string& value);
   void print_qualifiers(const QualifierSet& qualifiers);
   void print_enumerator(int64_t val, const std::string& name);
diff --git a/oi/type_graph/Prune.cpp b/oi/type_graph/Prune.cpp
index 903a8c2..8effd3b 100644
--- a/oi/type_graph/Prune.cpp
+++ b/oi/type_graph/Prune.cpp
@@ -39,18 +39,7 @@ void Prune::accept(Type& type) {
 }
 
 void Prune::visit(Class& c) {
-  for (const auto& param : c.templateParams) {
-    accept(param.type());
-  }
-  for (const auto& parent : c.parents) {
-    accept(parent.type());
-  }
-  for (const auto& member : c.members) {
-    accept(member.type());
-  }
-  for (const auto& child : c.children) {
-    accept(child);
-  }
+  RecursiveVisitor::visit(c);
 
   c.templateParams.clear();
   c.parents.clear();
@@ -62,4 +51,10 @@ void Prune::visit(Class& c) {
   c.functions.shrink_to_fit();
 }
 
+void Prune::visit(Container& c) {
+  RecursiveVisitor::visit(c);
+
+  c.setUnderlying(nullptr);
+}
+
 }  // namespace oi::detail::type_graph
diff --git a/oi/type_graph/Prune.h b/oi/type_graph/Prune.h
index d444ea3..c0701db 100644
--- a/oi/type_graph/Prune.h
+++ b/oi/type_graph/Prune.h
@@ -43,6 +43,7 @@ class Prune : public RecursiveVisitor {
 
   void accept(Type& type) override;
   void visit(Class& c) override;
+  void visit(Container& c) override;
 
  private:
   NodeTracker& tracker_;
diff --git a/oi/type_graph/TypeIdentifier.cpp b/oi/type_graph/TypeIdentifier.cpp
index 17fa43a..bba08f8 100644
--- a/oi/type_graph/TypeIdentifier.cpp
+++ b/oi/type_graph/TypeIdentifier.cpp
@@ -79,7 +79,8 @@ void TypeIdentifier::visit(Container& c) {
               it != passThroughTypeDummys_.end()) {
             dummy = &it->second.get();
           } else {
-            dummy = &typeGraph_.makeType<Container>(info, param.type().size());
+            dummy = &typeGraph_.makeType<Container>(
+                info, param.type().size(), paramClass);
             dummy->templateParams = paramClass->templateParams;
             passThroughTypeDummys_.insert(it,
                                           {paramClass->id(), std::ref(*dummy)});
diff --git a/oi/type_graph/Types.h b/oi/type_graph/Types.h
index dfb0806..e05d224 100644
--- a/oi/type_graph/Types.h
+++ b/oi/type_graph/Types.h
@@ -150,7 +150,6 @@ struct Function {
   int virtuality;
 };
 
-class Class;
 struct Parent {
   Parent(Type& type, uint64_t bitOffset) : type_(type), bitOffset(bitOffset) {
   }
@@ -298,10 +297,6 @@ class Class : public Type {
 
   DECLARE_ACCEPT
 
-  Kind kind() const {
-    return kind_;
-  }
-
   virtual const std::string& name() const override {
     return name_;
   }
@@ -326,12 +321,16 @@ class Class : public Type {
     return align_;
   }
 
+  void setAlign(uint64_t alignment) {
+    align_ = alignment;
+  }
+
   virtual NodeId id() const override {
     return id_;
   }
 
-  void setAlign(uint64_t alignment) {
-    align_ = alignment;
+  Kind kind() const {
+    return kind_;
   }
 
   int virtuality() const {
@@ -371,10 +370,19 @@ class Class : public Type {
   bool packed_ = false;
 };
 
+/*
+ * Container
+ *
+ * A type of class for which we can do special processing.
+ */
 class Container : public Type {
  public:
-  Container(NodeId id, const ContainerInfo& containerInfo, size_t size)
+  Container(NodeId id,
+            const ContainerInfo& containerInfo,
+            size_t size,
+            Type* underlying)
       : containerInfo_(containerInfo),
+        underlying_(underlying),
         name_(containerInfo.typeName),
         inputName_(containerInfo.typeName),
         size_(size),
@@ -386,6 +394,7 @@ class Container : public Type {
             const ContainerInfo& containerInfo)
       : templateParams(other.templateParams),
         containerInfo_(containerInfo),
+        underlying_(other.underlying_),
         name_(other.name_),
         inputName_(other.inputName_),
         size_(other.size_),
@@ -396,22 +405,18 @@ class Container : public Type {
 
   DECLARE_ACCEPT
 
-  const std::string& containerName() const {
-    return containerInfo_.typeName;
-  }
-
   virtual const std::string& name() const override {
     return name_;
   }
 
-  void setName(std::string name) {
-    name_ = std::move(name);
-  }
-
   virtual std::string_view inputName() const override {
     return inputName_;
   }
 
+  void setName(std::string name) {
+    name_ = std::move(name);
+  }
+
   void setInputName(std::string name) {
     inputName_ = std::move(name);
   }
@@ -424,18 +429,31 @@ class Container : public Type {
     return align_;
   }
 
+  void setAlign(uint64_t alignment) {
+    align_ = alignment;
+  }
+
   virtual NodeId id() const override {
     return id_;
   }
 
-  void setAlign(uint64_t alignment) {
-    align_ = alignment;
+  const std::string& containerName() const {
+    return containerInfo_.typeName;
+  }
+
+  Type* underlying() const {
+    return underlying_;
+  }
+
+  void setUnderlying(Type* underlying) {
+    underlying_ = underlying;
   }
 
   std::vector<TemplateParam> templateParams;
   const ContainerInfo& containerInfo_;
 
  private:
+  Type* underlying_;
   std::string name_;
   std::string inputName_;
   size_t size_;
diff --git a/oi/type_graph/Visitor.h b/oi/type_graph/Visitor.h
index 68c2c26..a7f7eec 100644
--- a/oi/type_graph/Visitor.h
+++ b/oi/type_graph/Visitor.h
@@ -93,6 +93,7 @@ class RecursiveVisitor : public Visitor<void> {
     for (const auto& param : c.templateParams) {
       accept(param.type());
     }
+    accept(c.underlying());
   }
   virtual void visit(Primitive&) {
   }
@@ -126,6 +127,11 @@ class RecursiveMutator : public Visitor<Type&> {
  public:
   virtual ~RecursiveMutator() = default;
   virtual Type& mutate(Type&) = 0;
+  virtual Type* mutate(Type* type) {
+    if (type)
+      return &mutate(*type);
+    return nullptr;
+  }
   virtual Type& visit(Incomplete& i) {
     return i;
   }
@@ -148,6 +154,7 @@ class RecursiveMutator : public Visitor<Type&> {
     for (auto& param : c.templateParams) {
       param.setType(mutate(param.type()));
     }
+    c.setUnderlying(mutate(c.underlying()));
     return c;
   }
   virtual Type& visit(Primitive& p) {
diff --git a/test/TypeGraphParser.cpp b/test/TypeGraphParser.cpp
index 7b6f425..f54fe08 100644
--- a/test/TypeGraphParser.cpp
+++ b/test/TypeGraphParser.cpp
@@ -265,10 +265,11 @@ Type& TypeGraphParser::parseType(std::string_view& input, size_t rootIndent) {
 
     auto size = parseNumericAttribute(line, nodeTypeName, "size: ");
 
-    Container& c = typeGraph_.makeType<Container>(id, info, size);
+    Container& c = typeGraph_.makeType<Container>(id, info, size, nullptr);
     nodesById_.insert({id, c});
 
     parseParams(c, input, indent + 2);
+    parseUnderlying(c, input, indent + 2);
 
     type = &c;
   } else if (nodeTypeName == "Primitive") {
@@ -452,3 +453,26 @@ void TypeGraphParser::parseChildren(Class& c,
   // No more children for us - put back the line we just read
   input = origInput;
 }
+
+void TypeGraphParser::parseUnderlying(Container& c,
+                                      std::string_view& input,
+                                      size_t rootIndent) {
+  std::string_view origInput = input;
+  std::string_view line;
+  getline(input, line);
+
+  size_t indent = stripIndent(line);
+  if (indent != rootIndent) {
+    input = origInput;
+    return;
+  }
+
+  // Format: "Underlying"
+  if (!tryRemovePrefix(line, "Underlying")) {
+    input = origInput;
+    return;
+  }
+
+  Type& type = parseType(input, rootIndent + 2);
+  c.setUnderlying(&type);
+}
diff --git a/test/TypeGraphParser.h b/test/TypeGraphParser.h
index 626c4a4..640b706 100644
--- a/test/TypeGraphParser.h
+++ b/test/TypeGraphParser.h
@@ -34,6 +34,9 @@ class TypeGraphParser {
   void parseMembers(Class& c, std::string_view& input, size_t rootIndent);
   void parseFunctions(Class& c, std::string_view& input, size_t rootIndent);
   void parseChildren(Class& c, std::string_view& input, size_t rootIndent);
+  void parseUnderlying(Container& c,
+                       std::string_view& input,
+                       size_t rootIndent);
 };
 
 class TypeGraphParserError : public std::runtime_error {
diff --git a/test/test_add_children.cpp b/test/test_add_children.cpp
index aca046e..0d9fb75 100644
--- a/test/test_add_children.cpp
+++ b/test/test_add_children.cpp
@@ -106,7 +106,7 @@ TEST_F(AddChildrenTest, InheritancePolymorphic) {
                      Function: ~allocator
                      Function: allocate
                      Function: deallocate
-                 *
+*
              Function: ~B (virtual)
              Function: myfunc (virtual)
              Function: B
@@ -159,7 +159,7 @@ TEST_F(AddChildrenTest, InheritancePolymorphic) {
                      Function: ~allocator
                      Function: allocate
                      Function: deallocate
-                 *
+*
              Function: operator=
              Function: B
              Function: B
diff --git a/test/test_alignment_calc.cpp b/test/test_alignment_calc.cpp
index 5bc4573..2526cbe 100644
--- a/test/test_alignment_calc.cpp
+++ b/test/test_alignment_calc.cpp
@@ -58,16 +58,16 @@ TEST(AlignmentCalcTest, StructInContainer) {
           Member: n (offset: 0)
             Primitive: int8_t
           Member: n (offset: 8)
-            Primitive: int64_t
+            Primitive: int32_t
 )",
        R"(
 [0] Container: std::vector (size: 8)
       Param
-[1]     Class: MyClass (size: 16, align: 8)
+[1]     Class: MyClass (size: 16, align: 4)
           Member: n (offset: 0, align: 1)
             Primitive: int8_t
-          Member: n (offset: 8, align: 8)
-            Primitive: int64_t
+          Member: n (offset: 8, align: 4)
+            Primitive: int32_t
 )");
 }
 
@@ -264,3 +264,33 @@ TEST(AlignmentCalcTest, Typedef) {
               Primitive: int8_t
 )");
 }
+
+TEST(AlignmentCalcTest, Container) {
+  test(AlignmentCalc::createPass(),
+       R"(
+[0] Container: std::vector (size: 24)
+      Underlying
+[1]     Class: vector (size: 24)
+          Member: n (offset: 0)
+            Primitive: int8_t
+          Member: s (offset: 4)
+[2]         Struct: MyStruct (size: 8)
+              Member: n1 (offset: 0)
+                Primitive: int32_t
+              Member: n2 (offset: 4)
+                Primitive: int32_t
+)",
+       R"(
+[0] Container: std::vector (size: 24, align: 4)
+      Underlying
+[1]     Class: vector (size: 24, align: 4)
+          Member: n (offset: 0, align: 1)
+            Primitive: int8_t
+          Member: s (offset: 4, align: 4)
+[2]         Struct: MyStruct (size: 8, align: 4)
+              Member: n1 (offset: 0, align: 4)
+                Primitive: int32_t
+              Member: n2 (offset: 4, align: 4)
+                Primitive: int32_t
+)");
+}
diff --git a/test/test_codegen.cpp b/test/test_codegen.cpp
index 660c411..a74b740 100644
--- a/test/test_codegen.cpp
+++ b/test/test_codegen.cpp
@@ -45,6 +45,8 @@ void testTransform(OICodeGen::Config& config,
 
 void testTransform(std::string_view input, std::string_view expectedAfter) {
   OICodeGen::Config config;
+  config.features[Feature::PruneTypeGraph] = true;
+  config.features[Feature::TreeBuilderV2] = true;
   testTransform(config, input, expectedAfter);
 }
 }  // namespace
@@ -62,7 +64,7 @@ TEST(CodeGenTest, TransformContainerAllocator) {
           Function: deallocate
 )",
                 R"(
-[2] Container: std::vector<int32_t, DummyAllocator<int32_t, 8, 1, 3>> (size: 24)
+[2] Container: std::vector<int32_t, DummyAllocator<int32_t, 8, 1, 3>> (size: 24, align: 1)
       Param
         Primitive: int32_t
       Param
@@ -95,14 +97,14 @@ TEST(CodeGenTest, TransformContainerAllocatorParamInParent) {
           Function: deallocate
 )",
                 R"(
-[4] Container: std::map<int32_t, int32_t, DummyAllocator<std::pair<int32_t const, int32_t>, 0, 1, 6>> (size: 24)
+[4] Container: std::map<int32_t, int32_t, DummyAllocator<std::pair<int32_t const, int32_t>, 0, 1, 6>> (size: 24, align: 1)
       Param
         Primitive: int32_t
       Param
         Primitive: int32_t
       Param
 [6]     DummyAllocator [MyAlloc<std::pair<const int, int>>] (size: 0, align: 1)
-[5]       Container: std::pair<int32_t const, int32_t> (size: 8)
+[5]       Container: std::pair<int32_t const, int32_t> (size: 8, align: 1)
             Param
               Primitive: int32_t
               Qualifiers: const
@@ -168,7 +170,7 @@ TEST(CodeGenTest, ReplaceContainersAndDummies) {
           Function: deallocate
 )",
                 R"(
-[2] Container: std::vector<uint32_t, DummyAllocator<uint32_t, 0, 1, 3>> (size: 24)
+[2] Container: std::vector<uint32_t, DummyAllocator<uint32_t, 0, 1, 3>> (size: 24, align: 1)
       Param
         Primitive: uint32_t
       Param
@@ -176,3 +178,73 @@ TEST(CodeGenTest, ReplaceContainersAndDummies) {
           Primitive: uint32_t
 )");
 }
+
+TEST(CodeGenTest, ContainerAlignment) {
+  testTransform(R"(
+[0] Class: MyClass (size: 24)
+      Member: container (offset: 0)
+[1]     Class: std::vector (size: 24)
+          Param
+            Primitive: int32_t
+          Member: __impl__ (offset: 0)
+            Primitive: StubbedPointer
+          Member: __impl__ (offset: 8)
+            Primitive: StubbedPointer
+          Member: __impl__ (offset: 16)
+            Primitive: StubbedPointer
+)",
+                R"(
+[0] Class: MyClass_0 [MyClass] (size: 24, align: 8)
+      Member: container_0 [container] (offset: 0, align: 8)
+[2]     Container: std::vector<int32_t> (size: 24, align: 8)
+          Param
+            Primitive: int32_t
+)");
+}
+
+TEST(CodeGenTest, InheritFromContainer) {
+  testTransform(R"(
+[0] Class: MyClass (size: 24)
+      Parent (offset: 0)
+[1]     Class: std::vector (size: 24)
+          Param
+            Primitive: int32_t
+          Member: __impl__ (offset: 0)
+            Primitive: StubbedPointer
+          Member: __impl__ (offset: 8)
+            Primitive: StubbedPointer
+          Member: __impl__ (offset: 16)
+            Primitive: StubbedPointer
+)",
+                R"(
+[0] Class: MyClass_0 [MyClass] (size: 24, align: 8)
+      Member: __oi_parent_0 [__oi_parent] (offset: 0, align: 8)
+[2]     Container: std::vector<int32_t> (size: 24, align: 8)
+          Param
+            Primitive: int32_t
+)");
+}
+
+TEST(CodeGenTest, InheritFromContainerCompat) {
+  OICodeGen::Config config;
+  testTransform(config,
+                R"(
+[0] Class: MyClass (size: 24)
+      Parent (offset: 0)
+[1]     Class: std::vector (size: 24)
+          Param
+            Primitive: int32_t
+          Member: __impl__ (offset: 0)
+            Primitive: StubbedPointer
+          Member: __impl__ (offset: 8)
+            Primitive: StubbedPointer
+          Member: __impl__ (offset: 16)
+            Primitive: StubbedPointer
+)",
+                R"(
+[0] Class: MyClass_0 [MyClass] (size: 24, align: 8)
+      Member: __oi_padding_0 (offset: 0)
+[3]     Array: [int8_t[24]] (length: 24)
+          Primitive: int8_t
+)");
+}
diff --git a/test/test_flattener.cpp b/test/test_flattener.cpp
index eab3cf8..808f4ee 100644
--- a/test/test_flattener.cpp
+++ b/test/test_flattener.cpp
@@ -799,6 +799,27 @@ TEST(FlattenerTest, ParentClassAndContainer) {
 )");
 }
 
+TEST(FlattenerTest, ContainerWithParent) {
+  // This is necessary to correctly calculate container alignment
+  test(Flattener::createPass(),
+       R"(
+[0] Container: std::vector (size: 24)
+      Underlying
+[1]     Class: vector (size: 24)
+          Parent (offset: 0)
+[2]         Class: Parent (size: 4)
+              Member: x (offset: 0)
+                Primitive: int32_t
+)",
+       R"(
+[0] Container: std::vector (size: 24)
+      Underlying
+[1]     Class: vector (size: 24)
+          Member: x (offset: 0)
+            Primitive: int32_t
+)");
+}
+
 TEST(FlattenerTest, AllocatorParamInParent) {
   test(Flattener::createPass(),
        R"(
@@ -857,7 +878,7 @@ TEST(FlattenerTest, AllocatorUnfixableNoParent) {
 )");
 }
 
-TEST(FlattenerTest, AllocatorUnfixableParentNotClass) {
+TEST(FlattenerTest, AllocatorParamInParentContainer) {
   // This could be supported if need-be, we just don't do it yet
   test(Flattener::createPass(),
        R"(
diff --git a/test/test_identify_containers.cpp b/test/test_identify_containers.cpp
index 4c359eb..3c42231 100644
--- a/test/test_identify_containers.cpp
+++ b/test/test_identify_containers.cpp
@@ -27,6 +27,12 @@ TEST(IdentifyContainers, Container) {
 [1] Container: std::vector (size: 24)
       Param
         Primitive: int32_t
+      Underlying
+[0]     Class: std::vector (size: 24)
+          Param
+            Primitive: int32_t
+          Member: a (offset: 0)
+            Primitive: int32_t
 )");
 }
 
@@ -52,14 +58,26 @@ TEST(IdentifyContainers, ContainerInClass) {
 [4]     Container: std::vector (size: 24)
           Param
             Primitive: int32_t
+          Underlying
+[1]         Class: std::vector (size: 24)
+              Param
+                Primitive: int32_t
       Parent (offset: 0)
 [5]     Container: std::vector (size: 24)
           Param
             Primitive: int32_t
+          Underlying
+[2]         Class: std::vector (size: 24)
+              Param
+                Primitive: int32_t
       Member: a (offset: 0)
 [6]     Container: std::vector (size: 24)
           Param
             Primitive: int32_t
+          Underlying
+[3]         Class: std::vector (size: 24)
+              Param
+                Primitive: int32_t
 )");
 }
 
@@ -77,6 +95,14 @@ TEST(IdentifyContainers, ContainerInContainer) {
 [3]     Container: std::vector (size: 24)
           Param
             Primitive: int32_t
+          Underlying
+[1]         Class: std::vector (size: 24)
+              Param
+                Primitive: int32_t
+      Underlying
+[0]     Class: std::vector (size: 24)
+          Param
+            [1]
 )");
 }
 
@@ -94,6 +120,10 @@ TEST(IdentifyContainers, ContainerInContainer2) {
 [2]     Container: std::vector (size: 24)
           Param
             Primitive: int32_t
+          Underlying
+[1]         Class: std::vector (size: 24)
+              Param
+                Primitive: int32_t
 )");
 }
 
@@ -109,6 +139,10 @@ TEST(IdentifyContainers, ContainerInArray) {
 [2]   Container: std::vector (size: 24)
         Param
           Primitive: int32_t
+        Underlying
+[1]       Class: std::vector (size: 24)
+            Param
+              Primitive: int32_t
 )");
 }
 
@@ -124,6 +158,10 @@ TEST(IdentifyContainers, ContainerInTypedef) {
 [2]   Container: std::vector (size: 24)
         Param
           Primitive: int32_t
+        Underlying
+[1]       Class: std::vector (size: 24)
+            Param
+              Primitive: int32_t
 )");
 }
 
@@ -139,6 +177,10 @@ TEST(IdentifyContainers, ContainerInPointer) {
 [2]   Container: std::vector (size: 24)
         Param
           Primitive: int32_t
+        Underlying
+[1]       Class: std::vector (size: 24)
+            Param
+              Primitive: int32_t
 )");
 }
 
@@ -155,6 +197,12 @@ TEST(IdentifyContainers, ContainerDuplicate) {
 [1] Container: std::vector (size: 24)
       Param
         Primitive: int32_t
+      Underlying
+[0]     Class: std::vector (size: 24)
+          Param
+            Primitive: int32_t
+          Member: a (offset: 0)
+            Primitive: int32_t
     [1]
 )");
 }
@@ -190,5 +238,9 @@ TEST(IdentifyContainers, CycleContainer) {
 [2]     Container: std::vector (size: 0)
           Param
             [0]
+          Underlying
+[1]         Class: std::vector (size: 0)
+              Param
+                [0]
 )");
 }
diff --git a/test/test_prune.cpp b/test/test_prune.cpp
index 3ae5d61..ad8ceee 100644
--- a/test/test_prune.cpp
+++ b/test/test_prune.cpp
@@ -63,3 +63,33 @@ TEST(PruneTest, RecurseClassChild) {
 [1]     Class: ClassA (size: 12)
 )");
 }
+
+TEST(PruneTest, PruneContainer) {
+  test(Prune::createPass(),
+       R"(
+[0] Container: std::vector (size: 24)
+      Param
+        Primitive: int32_t
+      Param
+        Value: "123"
+        Primitive: int32_t
+      Underlying
+[1]     Class: vector<int32_t> (size: 24)
+          Parent (offset: 0)
+[2]         Class: MyParent (size: 4)
+              Member: a (offset: 0)
+                Primitive: int32_t
+          Member: a (offset: 0)
+            Primitive: int32_t
+          Member: b (offset: 4)
+            Primitive: int32_t
+)",
+       R"(
+[0] Container: std::vector (size: 24)
+      Param
+        Primitive: int32_t
+      Param
+        Value: "123"
+        Primitive: int32_t
+)");
+}
diff --git a/test/test_type_identifier.cpp b/test/test_type_identifier.cpp
index b2b8c8c..ec9efd5 100644
--- a/test/test_type_identifier.cpp
+++ b/test/test_type_identifier.cpp
@@ -108,6 +108,12 @@ TEST(TypeIdentifierTest, PassThroughTypes) {
 [2]     Container: std::allocator (size: 1)
           Param
             Primitive: int32_t
+          Underlying
+[1]         Class: std::allocator (size: 1)
+              Param
+                Primitive: int32_t
+              Function: allocate
+              Function: deallocate
 )");
 }
 
@@ -137,6 +143,12 @@ TEST(TypeIdentifierTest, PassThroughSameType) {
 [2]     Container: std::allocator (size: 1)
           Param
             Primitive: int32_t
+          Underlying
+[1]         Class: std::allocator (size: 1)
+              Param
+                Primitive: int32_t
+              Function: allocate
+              Function: deallocate
       Param
         [2]
 )");
diff --git a/test/type_graph_utils.cpp b/test/type_graph_utils.cpp
index 815a46a..2d5709f 100644
--- a/test/type_graph_utils.cpp
+++ b/test/type_graph_utils.cpp
@@ -86,22 +86,23 @@ std::vector<std::unique_ptr<ContainerInfo>> getContainerInfos() {
 Container getVector(NodeId id) {
   static ContainerInfo info{"std::vector", SEQ_TYPE, "vector"};
   info.stubTemplateParams = {1};
-  return Container{id, info, 24};
+  return Container{id, info, 24, nullptr};
 }
 
 Container getMap(NodeId id) {
   static ContainerInfo info{"std::map", STD_MAP_TYPE, "map"};
   info.stubTemplateParams = {2, 3};
-  return Container{id, info, 48};
+  return Container{id, info, 48, nullptr};
 }
 
 Container getList(NodeId id) {
   static ContainerInfo info{"std::list", LIST_TYPE, "list"};
   info.stubTemplateParams = {1};
-  return Container{id, info, 24};
+  return Container{id, info, 24, nullptr};
 }
 
 Container getPair(NodeId id) {
   static ContainerInfo info{"std::pair", PAIR_TYPE, "utility"};
-  return Container{id, info, 8};  // Nonsense size, shouldn't matter for tests
+  return Container{
+      id, info, 8, nullptr};  // Nonsense size, shouldn't matter for tests
 }