diff --git a/src/libCom/iocsh/iocsh.cpp b/src/libCom/iocsh/iocsh.cpp
index f2d42b973..a3cbd22a1 100644
--- a/src/libCom/iocsh/iocsh.cpp
+++ b/src/libCom/iocsh/iocsh.cpp
@@ -798,7 +798,8 @@ iocshBody (const char *pathname, const char *commandLine)
 int epicsShareAPI
 iocsh (const char *pathname)
 {
-    epicsEnvSet("IOCSH_STARTUP_SCRIPT", pathname);
+    if (pathname)
+        epicsEnvSet("IOCSH_STARTUP_SCRIPT", pathname);
     return iocshBody(pathname, NULL);
 }