diff --git a/massif/ms_main.c b/massif/ms_main.c
index 55be3c2..6c1fc67 100644
--- a/massif/ms_main.c
+++ b/massif/ms_main.c
@@ -35,6 +35,7 @@
 // structures below for more info on how things work.
 
 #include "tool.h"
+#include "pub_tool_hashtable.h"
 #include "pub_tool_mallocfree.h"
 #include "pub_tool_replacemalloc.h"
 #include "pub_tool_stacktrace.h"