diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index c029fbb..79dead3 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -730,3 +730,11 @@
 	while (1)
 		;
 }
+
+void __assert_fail(const char *assertion, const char *file, unsigned line,
+		   const char *function)
+{
+	/* This will not return */
+	panic("%s:%u: %s: Assertion `%s' failed.", file, line, function,
+	      assertion);
+}