diff --git a/pkgs/development/compilers/gcc/10/default.nix b/pkgs/development/compilers/gcc/10/default.nix
index 2f7991a92124..93f8f278dc30 100644
--- a/pkgs/development/compilers/gcc/10/default.nix
+++ b/pkgs/development/compilers/gcc/10/default.nix
@@ -103,9 +103,15 @@ stdenv.mkDerivation ({
 
   hardeningDisable = [ "format" "pie" ];
 
+  postPatch = ''
+    configureScripts=$(find . -name configure)
+    for configureScript in $configureScripts; do
+      patchShebangs $configureScript
+    done
+  ''
   # This should kill all the stdinc frameworks that gcc and friends like to
   # insert into default search paths.
-  prePatch = lib.optionalString hostPlatform.isDarwin ''
+  + lib.optionalString hostPlatform.isDarwin ''
     substituteInPlace gcc/config/darwin-c.c \
       --replace 'if (stdinc)' 'if (0)'
 
@@ -114,14 +120,8 @@ stdenv.mkDerivation ({
 
     substituteInPlace libgfortran/configure \
       --replace "-install_name \\\$rpath/\\\$soname" "-install_name ''${!outputLib}/lib/\\\$soname"
-  '';
-
-  postPatch = ''
-    configureScripts=$(find . -name configure)
-    for configureScript in $configureScripts; do
-      patchShebangs $configureScript
-    done
-  '' + (
+  ''
+  + (
     if targetPlatform != hostPlatform || stdenv.cc.libc != null then
       # On NixOS, use the right path to the dynamic linker instead of
       # `/lib/ld*.so'.
diff --git a/pkgs/development/compilers/gcc/11/default.nix b/pkgs/development/compilers/gcc/11/default.nix
index 3a9f50be3e7f..8bd1abe8f97f 100644
--- a/pkgs/development/compilers/gcc/11/default.nix
+++ b/pkgs/development/compilers/gcc/11/default.nix
@@ -103,9 +103,15 @@ stdenv.mkDerivation ({
 
   hardeningDisable = [ "format" "pie" ];
 
+  postPatch = ''
+    configureScripts=$(find . -name configure)
+    for configureScript in $configureScripts; do
+      patchShebangs $configureScript
+    done
+  ''
   # This should kill all the stdinc frameworks that gcc and friends like to
   # insert into default search paths.
-  prePatch = lib.optionalString hostPlatform.isDarwin ''
+  + lib.optionalString hostPlatform.isDarwin ''
     substituteInPlace gcc/config/darwin-c.c \
       --replace 'if (stdinc)' 'if (0)'
 
@@ -114,14 +120,8 @@ stdenv.mkDerivation ({
 
     substituteInPlace libgfortran/configure \
       --replace "-install_name \\\$rpath/\\\$soname" "-install_name ''${!outputLib}/lib/\\\$soname"
-  '';
-
-  postPatch = ''
-    configureScripts=$(find . -name configure)
-    for configureScript in $configureScripts; do
-      patchShebangs $configureScript
-    done
-  '' + (
+  ''
+  + (
     if targetPlatform != hostPlatform || stdenv.cc.libc != null then
       # On NixOS, use the right path to the dynamic linker instead of
       # `/lib/ld*.so'.
diff --git a/pkgs/development/compilers/gcc/6/default.nix b/pkgs/development/compilers/gcc/6/default.nix
index 32a4ad0dd090..4e2a7d5e15f1 100644
--- a/pkgs/development/compilers/gcc/6/default.nix
+++ b/pkgs/development/compilers/gcc/6/default.nix
@@ -154,7 +154,7 @@ stdenv.mkDerivation ({
 
   hardeningDisable = [ "format" "pie" ];
 
-  prePatch =
+  postPatch =
     # This should kill all the stdinc frameworks that gcc and friends like to
     # insert into default search paths.
     lib.optionalString hostPlatform.isDarwin ''
@@ -166,9 +166,8 @@ stdenv.mkDerivation ({
 
       substituteInPlace libgfortran/configure \
         --replace "-install_name \\\$rpath/\\\$soname" "-install_name ''${!outputLib}/lib/\\\$soname"
-    '';
-
-  postPatch =
+    ''
+  + (
     if targetPlatform != hostPlatform || stdenv.cc.libc != null then
       # On NixOS, use the right path to the dynamic linker instead of
       # `/lib/ld*.so'.
@@ -191,7 +190,7 @@ stdenv.mkDerivation ({
             sed -i gcc/config/linux.h -e '1i#undef LOCAL_INCLUDE_DIR'
         ''
         )
-    else null;
+    else "");
 
   inherit noSysDirs staticCompiler langJava crossStageStatic
     libcCross crossMingw;
diff --git a/pkgs/development/compilers/gcc/7/default.nix b/pkgs/development/compilers/gcc/7/default.nix
index 33edc81ce539..28984887a954 100644
--- a/pkgs/development/compilers/gcc/7/default.nix
+++ b/pkgs/development/compilers/gcc/7/default.nix
@@ -114,9 +114,15 @@ stdenv.mkDerivation ({
 
   hardeningDisable = [ "format" "pie" ];
 
+  postPatch = ''
+    configureScripts=$(find . -name configure)
+    for configureScript in $configureScripts; do
+      patchShebangs $configureScript
+    done
+  ''
   # This should kill all the stdinc frameworks that gcc and friends like to
   # insert into default search paths.
-  prePatch = lib.optionalString hostPlatform.isDarwin ''
+  + lib.optionalString hostPlatform.isDarwin ''
     substituteInPlace gcc/config/darwin-c.c \
       --replace 'if (stdinc)' 'if (0)'
 
@@ -125,14 +131,8 @@ stdenv.mkDerivation ({
 
     substituteInPlace libgfortran/configure \
       --replace "-install_name \\\$rpath/\\\$soname" "-install_name ''${!outputLib}/lib/\\\$soname"
-  '';
-
-  postPatch = ''
-    configureScripts=$(find . -name configure)
-    for configureScript in $configureScripts; do
-      patchShebangs $configureScript
-    done
-  '' + (
+  ''
+  + (
     if targetPlatform != hostPlatform || stdenv.cc.libc != null then
       # On NixOS, use the right path to the dynamic linker instead of
       # `/lib/ld*.so'.
diff --git a/pkgs/development/compilers/gcc/8/default.nix b/pkgs/development/compilers/gcc/8/default.nix
index dae98afccb90..d811d1b3c73c 100644
--- a/pkgs/development/compilers/gcc/8/default.nix
+++ b/pkgs/development/compilers/gcc/8/default.nix
@@ -101,9 +101,15 @@ stdenv.mkDerivation ({
 
   hardeningDisable = [ "format" "pie" ];
 
+  postPatch = ''
+    configureScripts=$(find . -name configure)
+    for configureScript in $configureScripts; do
+      patchShebangs $configureScript
+    done
+  ''
   # This should kill all the stdinc frameworks that gcc and friends like to
   # insert into default search paths.
-  prePatch = lib.optionalString hostPlatform.isDarwin ''
+  + lib.optionalString hostPlatform.isDarwin ''
     substituteInPlace gcc/config/darwin-c.c \
       --replace 'if (stdinc)' 'if (0)'
 
@@ -112,14 +118,8 @@ stdenv.mkDerivation ({
 
     substituteInPlace libgfortran/configure \
       --replace "-install_name \\\$rpath/\\\$soname" "-install_name ''${!outputLib}/lib/\\\$soname"
-  '';
-
-  postPatch = ''
-    configureScripts=$(find . -name configure)
-    for configureScript in $configureScripts; do
-      patchShebangs $configureScript
-    done
-  '' + (
+  ''
+  + (
     if targetPlatform != hostPlatform || stdenv.cc.libc != null then
       # On NixOS, use the right path to the dynamic linker instead of
       # `/lib/ld*.so'.
diff --git a/pkgs/development/compilers/gcc/9/default.nix b/pkgs/development/compilers/gcc/9/default.nix
index ebe20e0cba5c..a0115b6f74e4 100644
--- a/pkgs/development/compilers/gcc/9/default.nix
+++ b/pkgs/development/compilers/gcc/9/default.nix
@@ -117,9 +117,15 @@ stdenv.mkDerivation ({
 
   hardeningDisable = [ "format" "pie" ];
 
+  postPatch = ''
+    configureScripts=$(find . -name configure)
+    for configureScript in $configureScripts; do
+      patchShebangs $configureScript
+    done
+  ''
   # This should kill all the stdinc frameworks that gcc and friends like to
   # insert into default search paths.
-  prePatch = lib.optionalString hostPlatform.isDarwin ''
+  + lib.optionalString hostPlatform.isDarwin ''
     substituteInPlace gcc/config/darwin-c.c \
       --replace 'if (stdinc)' 'if (0)'
 
@@ -128,14 +134,8 @@ stdenv.mkDerivation ({
 
     substituteInPlace libgfortran/configure \
       --replace "-install_name \\\$rpath/\\\$soname" "-install_name ''${!outputLib}/lib/\\\$soname"
-  '';
-
-  postPatch = ''
-    configureScripts=$(find . -name configure)
-    for configureScript in $configureScripts; do
-      patchShebangs $configureScript
-    done
-  '' + (
+  ''
+  + (
     if targetPlatform != hostPlatform || stdenv.cc.libc != null then
       # On NixOS, use the right path to the dynamic linker instead of
       # `/lib/ld*.so'.