diff --git a/loolwsd/LOOLSession.cpp b/loolwsd/LOOLSession.cpp
index a1667faf8..40064a4cc 100644
--- a/loolwsd/LOOLSession.cpp
+++ b/loolwsd/LOOLSession.cpp
@@ -81,7 +81,6 @@ void LOOLSession::sendBinaryFrame(const char *buffer, int length)
     _ws->sendFrame(buffer, length, WebSocket::FRAME_BINARY);
 }
 
-std::map<UInt64, MasterProcessSession*> MasterProcessSession::_childIdToChildSession;
 std::set<UInt64> MasterProcessSession::_pendingPreSpawnedChildren;
 std::set<MasterProcessSession*> MasterProcessSession::_availableChildSessions;
 std::map<Process::PID, UInt64> MasterProcessSession::_childProcesses;
@@ -172,7 +171,6 @@ bool MasterProcessSession::handleInput(char *buffer, int length)
         }
         _pendingPreSpawnedChildren.erase(childId);
         _availableChildSessions.insert(this);
-        _childIdToChildSession[childId] = this;
         _childId = childId;
     }
     else if (_kind == Kind::ToPrisoner)
diff --git a/loolwsd/LOOLSession.hpp b/loolwsd/LOOLSession.hpp
index 7b2cfd61b..a13e1aa88 100644
--- a/loolwsd/LOOLSession.hpp
+++ b/loolwsd/LOOLSession.hpp
@@ -122,10 +122,6 @@ protected:
     // per document being edited (i.e., per child process).
     MasterProcessSession *_peer;
 
-    // Map from child ids to the corresponding session to the child
-    // process.
-    static std::map<Poco::UInt64, MasterProcessSession*> _childIdToChildSession;
-
     // Pre-spawned child processes that haven't yet connected.
     static std::set<Poco::UInt64> _pendingPreSpawnedChildren;