diff --git a/src/account_factory.h b/src/account_factory.h
index 7f6a419b52055777a4c29107d282870cd5c1ffd6..35309498adf88d92e972958c8fd3b0d1be1c1c27 100644
--- a/src/account_factory.h
+++ b/src/account_factory.h
@@ -27,6 +27,7 @@
 #include <memory>
 #include <mutex>
 #include <utility>
+#include <functional>
 
 namespace ring {
 
diff --git a/src/call.h b/src/call.h
index dd885138e9e588b4078cad8fa75dc92e91ca2338..1caf770951f1dd0af70fcd793824ff081be0aad9 100644
--- a/src/call.h
+++ b/src/call.h
@@ -40,6 +40,7 @@
 #include <condition_variable>
 #include <set>
 #include <list>
+#include <functional>
 
 namespace ring {
 
diff --git a/src/sip/sipvoiplink.h b/src/sip/sipvoiplink.h
index 5a6595b518893f8e1d0b8906a58b59401903a92e..476a4c9d455c8113c3eace3a81d505b5449202c0 100644
--- a/src/sip/sipvoiplink.h
+++ b/src/sip/sipvoiplink.h
@@ -46,6 +46,7 @@
 #include <map>
 #include <mutex>
 #include <memory>
+#include <functional>
 
 namespace ring {
 
diff --git a/src/thread_pool.h b/src/thread_pool.h
index 716e9e957f57f5f329f4d5e6dab26e260a07d1c5..362210bf227ef84f68c3506884d6231d2f67664d 100644
--- a/src/thread_pool.h
+++ b/src/thread_pool.h
@@ -23,6 +23,7 @@
 #include <vector>
 #include <queue>
 #include <future>
+#include <functional>
 
 namespace ring {