diff --git a/kernel/kexec.c b/kernel/kexec.c
index 60bf181..7b08867 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1129,6 +1129,7 @@
 {
 	int ret = 0;
 	unsigned long start, end;
+	unsigned long old_size;
 	struct resource *ram_res;
 
 	mutex_lock(&kexec_mutex);
@@ -1139,11 +1140,9 @@
 	}
 	start = crashk_res.start;
 	end = crashk_res.end;
-
-	if (new_size >= end - start + 1) {
-		ret = -EINVAL;
-		if (new_size == end - start + 1)
-			ret = 0;
+	old_size = (end == 0) ? 0 : end - start + 1;
+	if (new_size >= old_size) {
+		ret = (new_size == old_size) ? 0 : -EINVAL;
 		goto unlock;
 	}