diff --git a/pkgs/development/compilers/gcc/4.8/default.nix b/pkgs/development/compilers/gcc/4.8/default.nix
index 2fb8f9d73b5..7b73559ba9c 100644
--- a/pkgs/development/compilers/gcc/4.8/default.nix
+++ b/pkgs/development/compilers/gcc/4.8/default.nix
@@ -59,10 +59,7 @@ let version = "4.8.3";
     # Whether building a cross-compiler for GNU/Hurd.
     crossGNU = cross != null && cross.config == "i586-pc-gnu";
 
-  /* gccinstall.info says that "parallel make is currently not supported since
-     collisions in profile collecting may occur".
-  */
-    enableParallelBuilding = !profiledCompiler;
+    enableParallelBuilding = true;
 
     patches = []
       ++ optional enableParallelBuilding ./parallel-bconfig.patch
diff --git a/pkgs/development/compilers/gcc/4.9/default.nix b/pkgs/development/compilers/gcc/4.9/default.nix
index 8b185d00bcc..f61e6b4445a 100644
--- a/pkgs/development/compilers/gcc/4.9/default.nix
+++ b/pkgs/development/compilers/gcc/4.9/default.nix
@@ -57,10 +57,7 @@ let version = "4.9.1";
     # Whether building a cross-compiler for GNU/Hurd.
     crossGNU = cross != null && cross.config == "i586-pc-gnu";
 
-  /* gccinstall.info says that "parallel make is currently not supported since
-     collisions in profile collecting may occur".
-  */
-    enableParallelBuilding = !profiledCompiler;
+    enableParallelBuilding = true;
 
     patches = [ ]
       ++ optional enableParallelBuilding ./parallel-bconfig.patch