diff --git a/src/libCom/test/blockingSockTest.cpp b/src/libCom/test/blockingSockTest.cpp
index fe7f4b3ff..41c56b76e 100644
--- a/src/libCom/test/blockingSockTest.cpp
+++ b/src/libCom/test/blockingSockTest.cpp
@@ -217,7 +217,7 @@ void blockingSockTest ()
 
     client.shutdown ();
     epicsThreadSleep ( 1.0 );
-    char * pStr = "esscimqi_?????";
+    const char * pStr = "esscimqi_?????";
     if ( client.recvWakeupDetected () ) {
         pStr = "esscimqi_socketBothShutdownRequired";
     }