diff --git a/util/histogram.h b/util/histogram.h
index 5ae816ca5..0cd11cac7 100644
--- a/util/histogram.h
+++ b/util/histogram.h
@@ -15,6 +15,8 @@
 #include <vector>
 #include <map>
 
+#include <string.h>
+
 namespace rocksdb {
 
 class HistogramBucketMapper {