diff --git a/libvmime.spec b/libvmime.spec
index 47878b9..8421eef 100644
--- a/libvmime.spec
+++ b/libvmime.spec
@@ -113,8 +113,10 @@ cf="%optflags -DVMIME_ALWAYS_GENERATE_7BIT_PARAMETER=1"
 	-DVMIME_HAVE_TLS_SUPPORT:BOOL=ON \
 	-DVMIME_BUILD_STATIC_LIBRARY:BOOL=OFF \
 	-DCMAKE_BUILD_TYPE:STRING="RelWithDebInfo" \
-	-DCMAKE_CXX_FLAGS:STRING="$cf" \
-	-DCMAKE_C_FLAGS:STRING="$cf"
+	-DCMAKE_CXX_FLAGS_RELWITHDEBINFO:STRING="$cf" \
+	-DCMAKE_CXX_FLAGS:STRING=" " \
+	-DCMAKE_C_FLAGS_RELWITHDEBINFO:STRING="$cf" \
+	-DCMAKE_C_FLAGS:STRING=" "
 make %{?_smp_mflags} VERBOSE=1
 
 %install