Index: uspace/lib/c/generic/assert.c
===================================================================
--- uspace/lib/c/generic/assert.c	(revision b1f0a141d37cd3a919a708e87dbff0bd6527788e)
+++ uspace/lib/c/generic/assert.c	(revision 33a3be89b1102f009ac56482a96315838ddfcd62)
@@ -46,6 +46,6 @@
 	 * Send the message safely to kio. Nested asserts should not occur.
 	 */
-	kio_printf("Assertion failed (%s) in task %ld, file \"%s\", line %u.\n",
-	    cond, (long) task_get_id(), file, line);
+	kio_printf("Assertion failed (%s) in task %" PRIu64 ", file \"%s\", line %u.\n",
+	    cond, task_get_id(), file, line);
 
 	stacktrace_kio_print();
@@ -60,6 +60,6 @@
 	 * Send the message safely to kio. Nested asserts should not occur.
 	 */
-	kio_printf("Assertion failed (%s) in task %ld, file \"%s\", line %u.\n",
-	    cond, (long) task_get_id(), file, line);
+	kio_printf("Assertion failed (%s) in task %" PRIu64 ", file \"%s\", line %u.\n",
+	    cond, task_get_id(), file, line);
 
 	stacktrace_kio_print();
@@ -77,6 +77,6 @@
 	 * assertions.
 	 */
-	kio_printf("Assertion failed (%s) in task %ld, file \"%s\", line %u.\n",
-	    cond, (long) task_get_id(), file, line);
+	kio_printf("Assertion failed (%s) in task %" PRIu64 ", file \"%s\", line %u.\n",
+	    cond, task_get_id(), file, line);
 	stacktrace_print();