diff --git a/sdk/include/opentelemetry/sdk/metrics/instruments.h b/sdk/include/opentelemetry/sdk/metrics/instruments.h
index 565fd05d95..22fdba2879 100644
--- a/sdk/include/opentelemetry/sdk/metrics/instruments.h
+++ b/sdk/include/opentelemetry/sdk/metrics/instruments.h
@@ -3,6 +3,7 @@
 
 #pragma once
 #ifndef ENABLE_METRICS_PREVIEW
+#  include <functional>
 #  include "opentelemetry/sdk/common/attribute_utils.h"
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace sdk