diff --git a/src/exec.cpp b/src/exec.cpp
index 8804c3e28..918d98fa3 100644
--- a/src/exec.cpp
+++ b/src/exec.cpp
@@ -21,6 +21,7 @@
 #include <algorithm>
 #include <map>
 #include <memory>
+#include <mutex>
 #include <string>
 #include <type_traits>
 #include <vector>