diff --git a/libbb/xgetlarg.c b/libbb/xgetlarg.c
index cadb83e..5b1e7b9 100644
--- a/libbb/xgetlarg.c
+++ b/libbb/xgetlarg.c
@@ -20,14 +20,8 @@
 	char *endptr;
 	int errno_save = errno;
 
-	assert(arg!=NULL);
-
-	/* Don't allow leading whitespace.
-	 * Wrap isspace in () to make sure we call the
-	 * function rather than the macro. */
-	if ((isspace)(*arg)) {
-		bb_show_usage();
-	}
+	if (ENABLE_DEBUG && arg==NULL)
+		bb_error_msg_and_die("Null in xgetlarg.");
 
 	errno = 0;
 	result = strtol(arg, &endptr, base);