diff --git a/dev/onewire.c b/dev/onewire.c
index 15827751456b7efc9f7b3d4f1c0b31ba19ce57c5..04fd5228d76e673b1c0f4b0a310291f43447802a 100644
--- a/dev/onewire.c
+++ b/dev/onewire.c
@@ -56,7 +56,8 @@ int8_t get_persistent_mac(uint8_t portnum, uint8_t * mac)
 
 	for (i = 0; i < devsnum; ++i) {
 //#if DEBUG_PMAC
-		mprintf("Found device: %x:%x:%x:%x:%x:%x:%x:%x\n",
+		mprintf("Found device: "
+			"%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x\n",
 		FamilySN[i][7], FamilySN[i][6], FamilySN[i][5], FamilySN[i][4],
 		FamilySN[i][3], FamilySN[i][2], FamilySN[i][1], FamilySN[i][0]);
 //#endif
@@ -89,7 +90,7 @@ int8_t get_persistent_mac(uint8_t portnum, uint8_t * mac)
 					out = 0;
 #if DEBUG_PMAC
 					mprintf("Using EEPROM page: "
-						"%x:%x:%x:%x:%x:%x\n",
+						"%02x:%02x:%02x:%02x:%02x:%02x\n",
 					     mac[0], mac[1], mac[2], mac[3],
 					     mac[4], mac[5]);
 #endif
diff --git a/shell/cmd_mac.c b/shell/cmd_mac.c
index 29386dc8eb3c6d167a9f0d4db247a5764bb6251e..0bd602e84d988cb66b5c77e8acb3fd87298ca330 100644
--- a/shell/cmd_mac.c
+++ b/shell/cmd_mac.c
@@ -44,7 +44,7 @@ int cmd_mac(const char *args[])
 		return -EINVAL;
 	}
 
-	mprintf("MAC-address: %x:%x:%x:%x:%x:%x\n",
+	mprintf("MAC-address: %02x:%02x:%02x:%02x:%02x:%02x\n",
 		mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
 	return 0;
 }