diff --git a/kernel/src/utils/string.c b/kernel/src/utils/string.c
index ec3bcd6..79fba97 100644
--- a/kernel/src/utils/string.c
+++ b/kernel/src/utils/string.c
@@ -71,7 +71,12 @@ uint64_t variadic_format_size(string_t string, va_list args) {
                 }
                 case 's': {
                     // string
-                    uint64_t strlen = string_length(va_arg(args, string_t));
+                    string_t str = va_arg(args, string_t);
+                    if (str == NULL) {
+                        str = "<string NULL reference>";
+                    }
+
+                    uint64_t strlen = string_length(str);
                     if (numeric_specifier > 0) {
                         strlen = MIN(strlen, numeric_specifier);
                     }
@@ -201,7 +206,10 @@ void variadic_format(string_t output, string_t string, va_list args) {
                 }
                 case 's': {
                     // string
-                    string_t str    = va_arg(args, string_t);
+                    string_t str = va_arg(args, string_t);
+                    if (str == NULL) {
+                        str = "<string NULL reference>";
+                    }
                     uint64_t strlen = string_length(str);
 
                     if (numeric_specifier > 0) {