diff --git a/src/math/hilbert/heap_trie.h b/src/math/hilbert/heap_trie.h
index 3c6ecd1cb..add64d2a0 100644
--- a/src/math/hilbert/heap_trie.h
+++ b/src/math/hilbert/heap_trie.h
@@ -37,13 +37,13 @@ Notes:
 #ifndef HEAP_TRIE_H_
 #define HEAP_TRIE_H_
 
+#include <cstring>
 #include "util/map.h"
 #include "util/vector.h"
 #include "util/buffer.h"
 #include "util/statistics.h"
 #include "util/small_object_allocator.h"
 
-
 template<typename Key, typename KeyLE, typename KeyHash, typename Value>
 class heap_trie {
 
diff --git a/src/test/mpff.cpp b/src/test/mpff.cpp
index c78489f21..83c500b49 100644
--- a/src/test/mpff.cpp
+++ b/src/test/mpff.cpp
@@ -16,7 +16,8 @@ Author:
 Revision History:
 
 --*/
-#include<sstream>
+#include <sstream>
+#include <cstring>
 #include "util/mpff.h"
 #include "util/mpz.h"
 #include "util/mpq.h"