diff --git a/Android.mk b/Android.mk
index b6ad701..1fb89e0 100644
--- a/Android.mk
+++ b/Android.mk
@@ -32,7 +32,7 @@
 LOCAL_CFLAGS_x86 += -DONLY_C
 LOCAL_CFLAGS_x86_64 += -DONLY_C
 
-LOCAL_CFLAGS+= -O2
+LOCAL_CFLAGS+= -O2 -funsigned-char
 
 LOCAL_C_INCLUDES:= \
 	$(LOCAL_PATH)/Tremolo