diff --git a/src/net.cpp b/src/net.cpp
index d6977882..37adc13e 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -1143,6 +1143,11 @@ void MapPort(bool fMapPort)
             printf("Error: ThreadMapPort(ThreadMapPort) failed\n");
     }
 }
+#else
+void MapPort(bool /* unused fMapPort */)
+{
+    // Intentionally left blank.
+}
 #endif