diff --git a/site_ansto/counterdriv.c b/site_ansto/counterdriv.c
index d8137f5e..11c29a70 100644
--- a/site_ansto/counterdriv.c
+++ b/site_ansto/counterdriv.c
@@ -278,7 +278,7 @@ static int MonRead(pBeamMon self, /*@out@*/ char* text, int *pLen) {
     status = readRS232TillTerm(self->controller, text, pLen);
     switch (status) {
       case 1:
-        if (pLen > 0)
+        if (*pLen > 0)
           flog(self, "<::%s", text);
         return SUCCESS;
       case TIMEOUT: