diff --git a/bootstrap b/bootstrap
index 47f7e769f6..6da87e774a 100755
--- a/bootstrap
+++ b/bootstrap
@@ -1056,6 +1056,7 @@ TMPFILE=`cmake_tmp_file`
 echo '
 #include <iostream>
 #include <memory>
+#include <unordered_map>
 
 #if __cplusplus < 201103L
 #error "Compiler is not in a mode aware of C++11."