diff --git a/Makefile b/Makefile
index 474655c..89c396c 100644
--- a/Makefile
+++ b/Makefile
@@ -31,9 +31,9 @@ OPT ?= -O3
 
 PREFIX ?= /usr/local
 
-CXXFLAGS ?= -g $(OPT) -Wall -Wextra -Woverloaded-virtual -pedantic -std=c++0x -fPIC
+CXXFLAGS += -Wall -Wextra -Woverloaded-virtual -pedantic -std=c++0x -fPIC
 CXXFLAGS += -Iinclude -Ithird_party/md5 -Ithird_party/json
-CFLAGS ?= -g $(OPT) -Wall -Wextra -pedantic -std=c99 -fPIC
+CFLAGS += -Wall -Wextra -pedantic -std=c99 -fPIC
 CFLAGS += -Iinclude
 MAKEDEPENDFLAGS += -Iinclude -Ithird_party/md5 -Ithird_party/json
 EMCXXFLAGS = $(CXXFLAGS) -g0 -Os --memory-init-file 0 -s DISABLE_EXCEPTION_CATCHING=0 -s OUTLINING_LIMIT=10000 -s RESERVED_FUNCTION_POINTERS=20 -s ASSERTIONS=1 -s ALLOW_MEMORY_GROWTH=1