diff --git a/drivers/acpi/sleep/proc.c b/drivers/acpi/sleep/proc.c
index 1538355..fce78fb 100644
--- a/drivers/acpi/sleep/proc.c
+++ b/drivers/acpi/sleep/proc.c
@@ -178,6 +178,9 @@
 	 * Try to find delimeter, only to insert null.  The end of the
 	 * string won't have one, but is still valid.
 	 */
+	if (*p == NULL)
+		return result;
+
 	next = strpbrk(*p, "- :");
 	if (next)
 		*next++ = '\0';
@@ -190,6 +193,8 @@
 
 	if (next)
 		*p = next;
+	else
+		*p = NULL;
 
 	return result;
 }