--- Makefile	2015-11-03 09:17:30.000000000 +0100
+++ Makefile	2015-11-06 14:26:08.884827907 +0100
@@ -37,6 +37,11 @@
 SANITIZE_ADDRESS=
 endif
 
+SANITIZE_UNDEFINED?=
+ifneq ($(SANITIZE_UNDEFINED), yes)
+SANITIZE_UNDEFINED=
+endif
+
 ifeq ($(OPTIMIZE),yes)
 BASE_CXXFLAGS += -O2
 endif
@@ -56,7 +61,7 @@
 GCC_GTEQ_490 := $(shell expr `$(CXX) -dumpversion | sed -e 's/\.\([0-9][0-9]\)/\1/g' -e 's/\.\([0-9]\)/0\1/g' -e 's/^[0-9]\{3,4\}$$/&00/'` \>= 40900)
 BASE_CXXFLAGS += -Wno-literal-suffix -Wno-sign-compare
 ifeq "$(GCC_GTEQ_490)" "1"
-BASE_CXXFLAGS += -fdiagnostics-color=auto -fsanitize=undefined
+BASE_CXXFLAGS += -fdiagnostics-color=auto
 endif
 endif
 
@@ -88,6 +93,11 @@
 LDFLAGS += -fsanitize=address
 endif
 
+# Check for sanitize-undefined option
+ifeq ($(SANITIZE_UNDEFINED), yes)
+BASE_CXXFLAGS += -fsanitize=undefined
+endif
+
 # Compiler include options, used after CXXFLAGS and CPPFLAGS.
 INC := -isystem external/include $(shell pkg-config --cflags x11 sdl2 glew SDL2_image SDL2_ttf libpng zlib freetype2 cairo)
 
@@ -162,6 +172,23 @@
 		$(LIBS) -lboost_regex -lboost_system -lboost_filesystem -lpthread -fthreadsafe-statics
 
 checkdirs: $(BUILD_DIR)
+	@echo -e \
+	 " OPTIMIZE            : $(OPTIMIZE)\n" \
+	  "USE_CCACHE          : $(USE_CCACHE)\n" \
+	  "CCACHE              : $(CCACHE)\n" \
+	  "SANITIZE_ADDRESS    : $(SANITIZE_ADDRESS)\n" \
+	  "SANITIZE_UNDEFINED  : $(SANITIZE_UNDEFINED)\n" \
+	  "USE_DB_CLIENT       : $(USE_DB_CLIENT)\n" \
+	  "USE_BOX2D           : $(USE_BOX2D)\n" \
+	  "USE_LIBVPX          : $(USE_LIBVPX)\n" \
+	  "USE_LUA             : $(USE_LUA)\n" \
+	  "USE_SDL2            : $(USE_SDL2)\n" \
+	  "CXX                 : $(CXX)\n" \
+	  "BASE_CXXFLAGS       : $(BASE_CXXFLAGS)\n" \
+	  "CXXFLAGS            : $(CXXFLAGS)\n" \
+	  "LDFLAGS             : $(LDFLAGS)\n" \
+	  "LIBS                : $(LIBS)"
+
 
 $(BUILD_DIR):
 	@mkdir -p $@