diff --git a/libowlps/libowlps.c b/libowlps/libowlps.c
index 08535e6..36e18b9 100644
--- a/libowlps/libowlps.c
+++ b/libowlps/libowlps.c
@@ -49,9 +49,10 @@ const char* owl_mac_bytes_to_string(const uint8_t *const mac_binary)
 void owl_mac_bytes_to_string_r(const uint8_t *const mac_binary,
                                char mac_str[OWL_ETHER_ADDR_STRLEN])
 {
-  sprintf(mac_str, "%02x:%02x:%02x:%02x:%02x:%02x",
-          mac_binary[0], mac_binary[1], mac_binary[2],
-          mac_binary[3], mac_binary[4], mac_binary[5]) ;
+  snprintf(mac_str, OWL_ETHER_ADDR_STRLEN,
+           "%02x:%02x:%02x:%02x:%02x:%02x",
+           mac_binary[0], mac_binary[1], mac_binary[2],
+           mac_binary[3], mac_binary[4], mac_binary[5]) ;
 }