diff --git a/pkgs/applications/graphics/rapcad/default.nix b/pkgs/applications/graphics/rapcad/default.nix
index 118630e9608..16c9e9fdff2 100644
--- a/pkgs/applications/graphics/rapcad/default.nix
+++ b/pkgs/applications/graphics/rapcad/default.nix
@@ -21,5 +21,6 @@ stdenv.mkDerivation rec {
     maintainers = [ maintainers.raskin ];
     platforms = platforms.linux;
     description = ''Constructive solid geometry package'';
+    broken = true; # redefines template instance added in Qt 5.6
   };
 }
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index e4a2f02b6b2..290ae99a17b 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -15182,7 +15182,7 @@ with pkgs;
     demo = false;
   };
 
-  rapcad = libsForQt55.callPackage ../applications/graphics/rapcad { boost = boost159; };
+  rapcad = libsForQt56.callPackage ../applications/graphics/rapcad { boost = boost159; };
 
   rapidsvn = callPackage ../applications/version-management/rapidsvn { };