diff --git a/common.pri b/common.pri
index 5d5e8870d9..ad3429d442 100644
--- a/common.pri
+++ b/common.pri
@@ -102,8 +102,10 @@ win32-msvc2010 {
 }
 
 unix|win32-g++ {
-  QMAKE_CXXFLAGS_WARN_ON *= -Wno-sign-compare -Wno-strict-aliasing -Wconversion -Wno-unused-parameter \
-                            -Wno-sign-conversion
+  QMAKE_CXXFLAGS_WARN_ON *= -Wno-sign-compare -Wno-strict-aliasing -Wconversion -Wno-unused-parameter
+  !*-g++42 {
+    QMAKE_CXXFLAGS_WARN_ON *= -Wno-sign-conversion
+  }
   # experimental
   QMAKE_CFLAGS_RELEASE -= -O2
   QMAKE_CFLAGS_RELEASE += -O3