diff --git a/config.mk b/config.mk
index 7b3b494..3b8b675 100644
--- a/config.mk
+++ b/config.mk
@@ -1,4 +1,5 @@
 PREFIX ?= /usr/local
+DEBUG ?= 0
 
 CXX ?= clang++
 CC ?= clang
@@ -6,12 +7,12 @@
 
 C_STD ?= c99
 CXX_STD ?= c++11
-ifeq ($(EMCC),1)
-OPT_LEVEL ?= 2
-DBG_LEVEL ?=
-else
+ifeq ($(DEBUG),1)
 OPT_LEVEL ?= 0
 DBG_LEVEL ?= -ggdb
+else
+OPT_LEVEL ?= 2
+DBG_LEVEL ?=
 endif
 WARN_LEVEL ?= all