diff --git a/tools/mkspecs/macx-clang/mac-clang.conf b/tools/mkspecs/macx-clang/mac-clang.conf
index 6ad9a0cdad..e8bcf91826 100644
--- a/tools/mkspecs/macx-clang/mac-clang.conf
+++ b/tools/mkspecs/macx-clang/mac-clang.conf
@@ -11,7 +11,7 @@ QMAKE_CFLAGS_DEPS	+= -M
 QMAKE_CFLAGS_WARN_ON	+= -Wall -W
 QMAKE_CFLAGS_WARN_OFF	+= -w
 QMAKE_CFLAGS_RELEASE	+= -O2
-QMAKE_CFLAGS_DEBUG	+= -g
+QMAKE_CFLAGS_DEBUG	+= -g -O0
 QMAKE_CFLAGS_SHLIB	+= -fPIC
 QMAKE_CFLAGS_STATIC_LIB	+=
 QMAKE_CFLAGS_YACC	+= -Wno-unused -Wno-parentheses
diff --git a/tools/mkspecs/macx-clang/qmake.conf b/tools/mkspecs/macx-clang/qmake.conf
index 2a43f17d8f..3c5241e517 100644
--- a/tools/mkspecs/macx-clang/qmake.conf
+++ b/tools/mkspecs/macx-clang/qmake.conf
@@ -21,5 +21,3 @@ QMAKE_LINK = clang++
 
 load(qt_config)
 
-QMAKE_CFLAGS += -Wno-unused-parameter
-QMAKE_CXXFLAGS += -Wno-unused-parameter