diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c b/arch/x86/kernel/cpu/mtrr/cleanup.c
index ac140c7..bdda2e6 100644
--- a/arch/x86/kernel/cpu/mtrr/cleanup.c
+++ b/arch/x86/kernel/cpu/mtrr/cleanup.c
@@ -266,7 +266,7 @@
 		if (align > max_align)
 			align = max_align;
 
-		sizek = 1 << align;
+		sizek = 1UL << align;
 		if (debug_print) {
 			char start_factor = 'K', size_factor = 'K';
 			unsigned long start_base, size_base;