diff --git a/pkgs/applications/science/astronomy/gildas/aarch64.patch b/pkgs/applications/science/astronomy/gildas/aarch64.patch
new file mode 100644
index 000000000000..40696a03dec7
--- /dev/null
+++ b/pkgs/applications/science/astronomy/gildas/aarch64.patch
@@ -0,0 +1,12 @@
+diff -ruN gildas-src-jul18a/admin/define-system.sh gildas-src-jul18a.aarch64/admin/define-system.sh
+--- gildas-src-jul18a/admin/define-system.sh	2018-06-12 15:22:32.000000000 +0200
++++ gildas-src-jul18a.aarch64/admin/define-system.sh	2018-07-21 13:05:52.000000000 +0200
+@@ -174,7 +174,7 @@
+     DEFAULT_CONFIG=          # Default config is empty
+     case `uname` in
+         Linux)
+-            if [ `uname -m | grep -c "x86_64"` -ne 0 ]; then
++            if [ `uname -m | grep -c "64"` -ne 0 ]; then
+         	GAG_MACHINE=x86_64
+             else
+         	GAG_MACHINE=pc
diff --git a/pkgs/applications/science/astronomy/gildas/default.nix b/pkgs/applications/science/astronomy/gildas/default.nix
index bd4587bf2276..7ede379fb499 100644
--- a/pkgs/applications/science/astronomy/gildas/default.nix
+++ b/pkgs/applications/science/astronomy/gildas/default.nix
@@ -7,13 +7,13 @@ let
 in
 
 stdenv.mkDerivation rec {
-  srcVersion = "jun18a";
-  version = "20180601_a";
+  srcVersion = "jul18a";
+  version = "20180701_a";
   name = "gildas-${version}";
 
   src = fetchurl {
-    url = "http://www.iram.fr/~gildas/dist/gildas-src-${srcVersion}.tar.gz";
-    sha256 = "0k4x0g69fphb1759cwcw6bbs8imwmq0qwj6zqixxk60skk4n4jvb";
+    url = "http://www.iram.fr/~gildas/dist/archive/gildas/gildas-src-${srcVersion}.tar.gz";
+    sha256 = "0kl3zf6b1kv8hgsfrarsnm2gnrdax3vi8f856249y4nxsa7lbv2i";
   };
 
   enableParallelBuilding = true;
@@ -22,20 +22,16 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ gtk2-x11 lesstif cfitsio python27Env ];
 
-  patches = [ ./wrapper.patch ./return-error-code.patch ./clang.patch ];
+  patches = [ ./wrapper.patch ./return-error-code.patch ./clang.patch ./mod.patch ./aarch64.patch ];
 
   configurePhase=''
     substituteInPlace admin/wrapper.sh --replace '%%OUT%%' $out
     substituteInPlace admin/wrapper.sh --replace '%%PYTHONHOME%%' ${python27Env}
+    substituteInPlace utilities/main/gag-makedepend.pl --replace '/usr/bin/perl' ${perl}/bin/perl
     source admin/gildas-env.sh -c gfortran -o openmp
     echo "gag_doc:        $out/share/doc/" >> kernel/etc/gag.dico.lcl
   '';
 
-  buildPhase=''
-    make depend
-    make
-  '';
-
   postInstall=''
     mkdir -p $out/bin
     cp -a ../gildas-exe-${srcVersion}/* $out
diff --git a/pkgs/applications/science/astronomy/gildas/mod.patch b/pkgs/applications/science/astronomy/gildas/mod.patch
new file mode 100644
index 000000000000..c917b4674f13
--- /dev/null
+++ b/pkgs/applications/science/astronomy/gildas/mod.patch
@@ -0,0 +1,17 @@
+diff -ruN gildas-src-jul18a/admin/Makefile.build gildas-src-jul18a.mod/admin/Makefile.build
+--- gildas-src-jul18a/admin/Makefile.build	2018-06-14 14:36:54.000000000 +0200
++++ gildas-src-jul18a.mod/admin/Makefile.build	2018-07-06 13:31:46.000000000 +0200
+@@ -291,6 +291,13 @@
+ 	win-$(LIB_IDENTITY)-und.def -o $@ $(FLDLIBS) $(LIB_DEPENDS) $(ADD_LIBS) $(SYS_LIBS))
+ endif
+ 
++# Dummy rules for modules just so that make consider the module a
++# valid dependency when first parsing the makefiles. This rule should
++# never be applied as the modules are a by-product of the compilation
++# of the object
++$(builddir)/%.mod:
++	echo "dummy" > /dev/null
++
+ # Fortran executables
+ $(bindir)/% : $(builddir)/%.o | $(bindir)
+ 	$(FC) $(ALL_FLDFLAGS) $< $(OBJECTS) -o $@ \