diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 7a50590ba96..19e2da4365e 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -3698,12 +3698,12 @@ let
     inherit fetchurl stdenv;
   };
 
-  gmp = import ../development/libraries/gmp {
+  gmp = makeOverridable (import ../development/libraries/gmp) {
     inherit stdenv fetchurl m4;
     cxx = false;
   };
 
-  gmpxx = gmp;
+  gmpxx = gmp.override { cxx = true; };
 
   goffice = import ../development/libraries/goffice {
     inherit fetchurl stdenv pkgconfig libgsf libxml2 cairo