diff --git a/run b/run
index 2c394c985..cf965328b 100755
--- a/run
+++ b/run
@@ -1,14 +1,14 @@
 #!/bin/sh
 
-if [ -z "$CMTCONFIG" ] ; then
-  echo "error: CMTCONFIG not defined"
+if [ -z "$BINARY_TAG" ] ; then
+  echo "error: BINARY_TAG not defined - make sure your environment is set up."
   exit 1
 fi
 
-run_cmd=$(dirname $0)/build.$CMTCONFIG/run
+run_cmd=$(dirname $0)/build.$BINARY_TAG/run
 if [ -e "$run_cmd" ] ; then
   exec $run_cmd "$@"
 else
-  echo "error: cannot find build.$CMTCONFIG/run, did you build?"
+  echo "error: cannot find build.$BINARY_TAG/run, did you build?"
   exit 1
 fi