diff --git a/client/src/util.c b/client/src/util.c
index 65e3295f9..6e6da4359 100644
--- a/client/src/util.c
+++ b/client/src/util.c
@@ -959,7 +959,7 @@ int hextobinstring_n(char *target, char *source, int sourcelen) {
 }
 
 // convert bytes to binary string
-int byte_2_binstr(char *target,  const uint8_t *source, size_t sourcelen) {
+void byte_2_binstr(char *target,  const uint8_t *source, size_t sourcelen) {
     //uint8_t *p = *source;
     for (int i = 0 ; i < sourcelen; ++i) {
         uint8_t b = *(source++);
diff --git a/client/src/util.h b/client/src/util.h
index bbae06fcf..c606113fe 100644
--- a/client/src/util.h
+++ b/client/src/util.h
@@ -122,7 +122,7 @@ int binarraytohex(char *target, const size_t targetlen, const char *source, size
 void binarraytobinstring(char *target,  char *source, int length);
 int binstring2binarray(uint8_t *target, char *source, int length);
 
-int byte_2_binstr(char *target,  const uint8_t *source, size_t sourcelen);
+void byte_2_binstr(char *target,  const uint8_t *source, size_t sourcelen);
 
 uint8_t GetParity(const uint8_t *bits, uint8_t type, int length);
 void wiegand_add_parity(uint8_t *target, uint8_t *source, uint8_t length);