diff --git a/src/include/cpu/amd/mtrr.h b/src/include/cpu/amd/mtrr.h
index b8b820c..e96dc90 100644
--- a/src/include/cpu/amd/mtrr.h
+++ b/src/include/cpu/amd/mtrr.h
@@ -65,7 +65,7 @@
 		);
 }
 
-static inline uint64_t get_top_of_mem_below_4gb(void)
+static inline uint32_t get_top_of_mem_below_4gb(void)
 {
 	return rdmsr(TOP_MEM).lo;
 }