diff --git a/include/internal/catch_test_case_registry_impl.hpp b/include/internal/catch_test_case_registry_impl.hpp
index b7a383a0..345b29d5 100644
--- a/include/internal/catch_test_case_registry_impl.hpp
+++ b/include/internal/catch_test_case_registry_impl.hpp
@@ -12,6 +12,7 @@
 #include <vector>
 #include <set>
 #include <sstream>
+#include <iostream>
 
 namespace Catch
 {