1 files changed, 4 insertions, 1 deletions

diff --git a/firmware/include/sprintf.h b/firmware/include/sprintf.h
index b07ac9dfb6..869b73eb13 100644
--- a/firmware/include/sprintf.h
+++ b/firmware/include/sprintf.h
@@ -32,6 +32,9 @@ int snprintf (char *buf, size_t size, const char *fmt, ...)
 int vsnprintf (char *buf, int size, const char *fmt, va_list ap);
 int fdprintf (int fd, const char *fmt, ...) ATTRIBUTE_PRINTF(2, 3);
 
-int vfnprintf(int (*push)(void *userp, unsigned char data), void *userp, const char *fmt, va_list ap);
+/* callback function is called for every output character (byte) with userp and
+ * should return 0 when ch is a char other than '\0' that should stop printing */
+int vuprintf(int (*push)(void *userp, unsigned char data),
+              void *userp, const char *fmt, va_list ap);
 
 #endif /* __SPRINTF_H__ */