diff --git a/arch/x86/cpu/mtrr.c b/arch/x86/cpu/mtrr.c
index 14c644e..260a008 100644
--- a/arch/x86/cpu/mtrr.c
+++ b/arch/x86/cpu/mtrr.c
@@ -26,6 +26,7 @@
 #include <asm/mp.h>
 #include <asm/msr.h>
 #include <asm/mtrr.h>
+#include <linux/log2.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -179,6 +180,9 @@
 	if (!gd->arch.has_mtrr)
 		return -ENOSYS;
 
+	if (!is_power_of_2(size))
+		return -EINVAL;
+
 	if (gd->arch.mtrr_req_count == MAX_MTRR_REQUESTS)
 		return -ENOSPC;
 	req = &gd->arch.mtrr_req[gd->arch.mtrr_req_count++];
@@ -223,6 +227,9 @@
 {
 	int mtrr;
 
+	if (!is_power_of_2(size))
+		return -EINVAL;
+
 	mtrr = get_free_var_mtrr();
 	if (mtrr < 0)
 		return mtrr;
diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h
index 384672e..d1aa86b 100644
--- a/arch/x86/include/asm/mtrr.h
+++ b/arch/x86/include/asm/mtrr.h
@@ -119,7 +119,7 @@
  *
  * @type:	Requested type (MTRR_TYPE_)
  * @start:	Start address
- * @size:	Size
+ * @size:	Size, must be power of 2
  *
  * @return:	0 on success, non-zero on failure
  */
@@ -144,8 +144,9 @@
  *
  * @type:	Requested type (MTRR_TYPE_)
  * @start:	Start address
- * @size:	Size
- * @return 0 on success, -ENOSPC if there are no more MTRRs
+ * @size:	Size, must be power of 2
+ * @return 0 on success, -EINVAL if size is not power of 2,
+ * -ENOSPC if there are no more MTRRs
  */
 int mtrr_set_next_var(uint type, uint64_t base, uint64_t size);