diff --git a/lib/libc/assert.c b/lib/libc/assert.c
index ff987b3be..c199de6f7 100644
--- a/lib/libc/assert.c
+++ b/lib/libc/assert.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2022, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -21,7 +21,7 @@
 void __dead2 __assert(const char *file, unsigned int line,
 		      const char *assertion)
 {
-	printf("ASSERT: %s:%d:%s\n", file, line, assertion);
+	printf("ASSERT: %s:%u:%s\n", file, line, assertion);
 	backtrace("assert");
 	console_flush();
 	plat_panic_handler();
@@ -29,7 +29,7 @@ void __dead2 __assert(const char *file, unsigned int line,
 #elif PLAT_LOG_LEVEL_ASSERT >= LOG_LEVEL_INFO
 void __dead2 __assert(const char *file, unsigned int line)
 {
-	printf("ASSERT: %s:%d\n", file, line);
+	printf("ASSERT: %s:%u\n", file, line);
 	backtrace("assert");
 	console_flush();
 	plat_panic_handler();
diff --git a/lib/libc/snprintf.c b/lib/libc/snprintf.c
index f34cefd6a..675d2430d 100644
--- a/lib/libc/snprintf.c
+++ b/lib/libc/snprintf.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2021, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2022, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -42,7 +42,7 @@ static void unsigned_num_print(char **s, size_t n, size_t *chars_printed,
 	char ascii_a = capitalise ? 'A' : 'a';
 
 	if (radix < 10) {
-		ERROR("snprintf: unsupported radix '%d'.", radix);
+		ERROR("snprintf: unsupported radix '%u'.", radix);
 		plat_panic_handler();
 		assert(0); /* Unreachable */
 	}