Fix a missing #include.

diff --git a/quittable_sleeper.h b/quittable_sleeper.h
index 71e49f7731de3d49359f32cf048bcb639a7294a0..6c449a7b3c6e9a24be098b0f532093e7431ef53b 100644 (file)
--- a/quittable_sleeper.h
+++ b/quittable_sleeper.h
@@ -9,6 +9,7 @@
 // All member functions on this class are thread-safe.
 
 #include <chrono>
+#include <condition_variable>
 #include <mutex>
 
 class QuittableSleeper {