diff --git a/Android.bp b/Android.bp
index 79d444b..e9e3f98 100644
--- a/Android.bp
+++ b/Android.bp
@@ -51,6 +51,7 @@
     cflags: [
         "-O2",
         "-D_GNU_SOURCE",
+        "-funsigned-char",
     ],
 
     local_include_dirs: ["Tremolo"],