diff --git a/ci/iwyu/mappings.imp b/ci/iwyu/mappings.imp
index 627e20127..ff6a9f562 100644
--- a/ci/iwyu/mappings.imp
+++ b/ci/iwyu/mappings.imp
@@ -3,6 +3,7 @@
 ## Include mappings
 
 # stdlib
+{ "include": [ "<bits/chrono.h>", private, "<chrono>", "public" ] },
 { "include": [ "<bits/cxxabi_forced.h>", private, "<mutex>", "public" ] },
 { "include": [ "<bits/cxxabi_forced.h>", private, "<vector>", "public" ] },
 { "include": [ "<bits/this_thread_sleep.h>", private, "<thread>", "public" ] },
diff --git a/cpp/mrc/tests/test_edges.cpp b/cpp/mrc/tests/test_edges.cpp
index 41aeaffde..d4e69488b 100644
--- a/cpp/mrc/tests/test_edges.cpp
+++ b/cpp/mrc/tests/test_edges.cpp
@@ -32,6 +32,7 @@
 #include <gtest/gtest.h>
 #include <rxcpp/rx.hpp>  // for observable_member
 
+#include <chrono>
 #include <memory>
 #include <stdexcept>
 #include <utility>