diff --git a/Makefile b/Makefile
index d4dccf61..b610ea84 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,7 @@ ifeq ($(WINDOWS), 1)
 endif
 
 ifeq ($(RELEASE), 1)
-	ALL_CXXFLAGS += -O3
+	ALL_CXXFLAGS += -O3 -DNDEBUG
 	ALL_LDFLAGS += -s
 	FILENAME_DEF = CSE2$(EXE_EXTENSION)
 	DOCONFIG_FILENAME_DEF = DoConfig$(EXE_EXTENSION)