diff --git a/thirdparty/misc/base64.h b/thirdparty/misc/base64.h
index 4c300382c1c..ffcd0af9734 100644
--- a/thirdparty/misc/base64.h
+++ b/thirdparty/misc/base64.h
@@ -11,8 +11,8 @@
 
 extern "C" {
 
-uint32_t base64_encode(char *to, char *from, uint32_t len);
-uint32_t base64_decode(char *to, char *from, uint32_t len);
+long base64_encode(char *to, char *from, unsigned int len);
+long base64_decode(char *to, char *from, unsigned int len);
 };
 
 #endif /* BASE64_H */