diff --git a/config.mk b/config.mk
index 3510f6c68..bdb872d11 100644
--- a/config.mk
+++ b/config.mk
@@ -21,7 +21,7 @@ INCS = -I. -I/usr/include -I${X11INC} `pkg-config --cflags libconfuse xft cairo`
 LIBS = -L/usr/lib -lc -L${X11LIB} -lX11 `pkg-config --libs libconfuse xft cairo` -lXext -lXrandr -lXinerama
 
 # flags
-CFLAGS = -std=gnu99 -ggdb3 -pipe -Wall -Wextra -Wundef -Wshadow -Wcast-align -Wwrite-strings -Wsign-compare -Wunused -Winit-self -Wpointer-arith -Wredundant-decls -Wmissing-prototypes -Wmissing-format-attribute -Wmissing-noreturn -O0 ${INCS} -DVERSION=\"${VERSION}\" -DRELEASE=\"${RELEASE}\"
+CFLAGS = -std=gnu99 -ggdb3 -pipe -Wall -Wextra -Wundef -Wshadow -Wcast-align -Wwrite-strings -Wsign-compare -Wunused -Winit-self -Wpointer-arith -Wredundant-decls -Wmissing-prototypes -Wmissing-format-attribute -Wmissing-noreturn -O3 ${INCS} -DVERSION=\"${VERSION}\" -DRELEASE=\"${RELEASE}\"
 LDFLAGS = -ggdb3 ${LIBS}
 CLIENTLDFLAGS = -ggdb3