diff --git a/pkgs/development/libraries/qt-4.x/4.8/default.nix b/pkgs/development/libraries/qt-4.x/4.8/default.nix
index 46f24a08b5e1..05b2c582cc27 100644
--- a/pkgs/development/libraries/qt-4.x/4.8/default.nix
+++ b/pkgs/development/libraries/qt-4.x/4.8/default.nix
@@ -176,13 +176,14 @@ stdenv.mkDerivation rec {
   enableParallelBuilding = true;
 
   NIX_CFLAGS_COMPILE =
-    optionalString stdenv.isLinux "-std=gnu++98" # gnu++ in (Obj)C flags is no good on Darwin
-    + optionalString (stdenv.isFreeBSD || stdenv.isDarwin)
-      " -I${glib.dev}/include/glib-2.0 -I${glib.out}/lib/glib-2.0/include"
-    + optionalString stdenv.isDarwin " -I${libcxx}/include/c++/v1";
+    # with gcc7 the warnings blow the log over Hydra's limit
+    [ "-Wno-expansion-to-defined" "-Wno-unused-local-typedefs" ]
+    ++ optional stdenv.isLinux "-std=gnu++98" # gnu++ in (Obj)C flags is no good on Darwin
+    ++ optionals (stdenv.isFreeBSD || stdenv.isDarwin)
+      [ "-I${glib.dev}/include/glib-2.0" "-I${glib.out}/lib/glib-2.0/include" ]
+    ++ optional stdenv.isDarwin "-I${libcxx}/include/c++/v1";
 
-  NIX_LDFLAGS = optionalString (stdenv.isFreeBSD || stdenv.isDarwin)
-    "-lglib-2.0";
+  NIX_LDFLAGS = optional (stdenv.isFreeBSD || stdenv.isDarwin) "-lglib-2.0";
 
   preBuild = optionalString stdenv.isDarwin ''
     # resolve "extra qualification on member" error