diff --git a/src/iocsh/iocsh.cpp b/src/iocsh/iocsh.cpp
index 6bd0fd5a0..b2708d33c 100644
--- a/src/iocsh/iocsh.cpp
+++ b/src/iocsh/iocsh.cpp
@@ -46,7 +46,7 @@ struct iocshVariable {
 };
 static struct iocshVariable *iocshVariableHead;
 static char iocshVarID[] = "iocshVar";
-static void varCallFunc(const iocshArgBuf *);
+extern "C" static void varCallFunc(const iocshArgBuf *);
 static epicsMutexId iocshTableMutex;
 static epicsThreadOnceId iocshTableOnceId = EPICS_THREAD_ONCE_INIT;