diff --git a/pkgs/applications/networking/browsers/firefox/packages.nix b/pkgs/applications/networking/browsers/firefox/packages.nix
index f8c1c0837553..3bdf3685a1f6 100644
--- a/pkgs/applications/networking/browsers/firefox/packages.nix
+++ b/pkgs/applications/networking/browsers/firefox/packages.nix
@@ -43,6 +43,7 @@ rec {
     };
     updateScript = callPackage ./update.nix {
       attrPath = "firefox-unwrapped";
+      versionKey = "ffversion";
     };
   };
 
@@ -67,6 +68,7 @@ rec {
     updateScript = callPackage ./update.nix {
       attrPath = "firefox-esr-52-unwrapped";
       ffversionSuffix = "esr";
+      versionKey = "ffversion";
     };
   };
 
@@ -92,6 +94,7 @@ rec {
     updateScript = callPackage ./update.nix {
       attrPath = "firefox-esr-60-unwrapped";
       versionSuffix = "esr";
+      versionKey = "ffversion";
     };
   };
 
diff --git a/pkgs/applications/networking/browsers/firefox/update.nix b/pkgs/applications/networking/browsers/firefox/update.nix
index 8cc03cf8212a..a831d8231187 100644
--- a/pkgs/applications/networking/browsers/firefox/update.nix
+++ b/pkgs/applications/networking/browsers/firefox/update.nix
@@ -9,6 +9,7 @@
 , attrPath
 , baseUrl ? "http://archive.mozilla.org/pub/firefox/releases/"
 , versionSuffix ? ""
+, versionKey ? "version"
 }:
 
 writeScript "update-${attrPath}" ''
@@ -28,5 +29,5 @@ writeScript "update-${attrPath}" ''
            sort --version-sort | \
            tail -n 1`
 
-  update-source-version ${attrPath} "$version"
+  update-source-version ${attrPath} "$version" "" "" ${versionKey}
 ''
diff --git a/pkgs/common-updater/scripts/update-source-version b/pkgs/common-updater/scripts/update-source-version
index 3e507660a65e..57b52553c2be 100755
--- a/pkgs/common-updater/scripts/update-source-version
+++ b/pkgs/common-updater/scripts/update-source-version
@@ -6,11 +6,16 @@ die() {
     exit 1
 }
 
-# Usage: update-source-hash <attr> <version> [<new-source-hash>] [<new-source-url>]
+# Usage: update-source-hash <attr> <version> [<new-source-hash>] [<new-source-url>] [<version-key>]
 attr=$1
 newVersion=$2
 newHash=$3
 newUrl=$4
+versionKey=$5
+
+if [ -z "$versionKey" ]; then
+    versionKey=version
+fi
 
 nixFile=$(nix-instantiate --eval --strict -A "$attr.meta.position" | sed -re 's/^"(.*):[0-9]+"$/\1/')
 if [ ! -f "$nixFile" ]; then
@@ -50,8 +55,8 @@ fi
 oldVersion=$(echo "$oldVersion" | sed -re 's|[.+]|\\&|g')
 oldUrl=$(echo "$oldUrl" | sed -re 's|[${}.+]|\\&|g')
 
-if [ $(grep -c -E "^\s*(let\b)?\s*version\s*=\s*\"$oldVersion\"" "$nixFile") = 1 ]; then
-    pattern="/\bversion\b\s*=/ s|\"$oldVersion\"|\"$newVersion\"|"
+if [ $(grep -c -E "^\s*(let\b)?\s*$versionKey\s*=\s*\"$oldVersion\"" "$nixFile") = 1 ]; then
+    pattern="/\b$versionKey\b\s*=/ s|\"$oldVersion\"|\"$newVersion\"|"
 elif [ $(grep -c -E "^\s*(let\b)?\s*name\s*=\s*\"[^\"]+-$oldVersion\"" "$nixFile") = 1 ]; then
     pattern="/\bname\b\s*=/ s|-$oldVersion\"|-$newVersion\"|"
 else