--- a/cmake/modules/FindKDE4Internal.cmake
+++ b/cmake/modules/FindKDE4Internal.cmake
@@ -1204,7 +1204,7 @@
    set(CMAKE_C_FLAGS_DEBUGFULL        "-g3 -fno-inline")
    set(CMAKE_C_FLAGS_PROFILE          "-g3 -fno-inline -ftest-coverage -fprofile-arcs")
 
-   set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS} -Wno-long-long -std=iso9899:1990 -Wundef -Wcast-align -Werror-implicit-function-declaration -Wchar-subscripts -Wall -W -Wpointer-arith -Wwrite-strings -Wformat-security -Wmissing-format-attribute -fno-common")
+   set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS} -Wno-long-long -std=iso9899:1990 -Wundef -Wcast-align -Wchar-subscripts -Wall -W -Wpointer-arith -Wwrite-strings -Wformat-security -Wmissing-format-attribute -fno-common")
    # As of Qt 4.6.x we need to override the new exception macros if we want compile with -fno-exceptions
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wnon-virtual-dtor -Wno-long-long -Wundef -Wcast-align -Wchar-subscripts -Wall -W -Wpointer-arith -Wformat-security -fno-exceptions -DQT_NO_EXCEPTIONS -fno-check-new -fno-common")
 
@@ -1295,7 +1295,7 @@
       endif(NOT _compile_result)
 
       if (GCC_IS_NEWER_THAN_4_2)
-         set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror=return-type -fvisibility-inlines-hidden")
+         set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility-inlines-hidden")
       endif (GCC_IS_NEWER_THAN_4_2)
    else (__KDE_HAVE_GCC_VISIBILITY AND GCC_IS_NEWER_THAN_4_1 AND NOT _GCC_COMPILED_WITH_BAD_ALLOCATOR AND NOT WIN32)
       set (__KDE_HAVE_GCC_VISIBILITY 0)