diff --git a/modules/mbedtls/debug.c b/modules/mbedtls/debug.c
index 3a1a478..3b2ede3 100644
--- a/modules/mbedtls/debug.c
+++ b/modules/mbedtls/debug.c
@@ -12,7 +12,7 @@
 
 void zephyr_mbedtls_debug(void *ctx, int level, const char *file, int line, const char *str)
 {
-	const char *p, *basename;
+	const char *p, *basename = file;
 
 	ARG_UNUSED(ctx);
 
@@ -21,9 +21,11 @@
 	}
 
 	/* Extract basename from file */
-	for (p = basename = file; *p != '\0'; p++) {
-		if (*p == '/' || *p == '\\') {
-			basename = p + 1;
+	if (IS_ENABLED(CONFIG_MBEDTLS_DEBUG_EXTRACT_BASENAME_AT_RUNTIME)) {
+		for (p = basename = file; *p != '\0'; p++) {
+			if (*p == '/' || *p == '\\') {
+				basename = p + 1;
+			}
 		}
 	}