diff --git a/src/vendormodules/commandstack-0.4.tm b/src/vendormodules/commandstack-0.4.tm
index 19c21289..165bd16a 100644
--- a/src/vendormodules/commandstack-0.4.tm
+++ b/src/vendormodules/commandstack-0.4.tm
@@ -167,6 +167,12 @@ namespace eval commandstack {
         lassign $arglist command procargs procbody
 
         set command [uplevel 1 [list namespace which $command]]
+        if {$command eq ""} {
+            #review
+            puts stderr "commandstack::rename_command no rename performed for command '$command' by '$renamer'. command '$command' not found in calling context. Ensure command name is fully qualified or that command exists."
+            #add something to stack?
+            return [dict create implementation ""]
+        }
         set mungedcommand [string map {:: _ns_} $command]
         set mungedrenamer [string map {:: _ns_} $renamer]
         variable all_stacks
@@ -284,7 +290,8 @@ namespace eval commandstack {
         ]
         if {![dict get $nextinfo do_rename]} {
             #review
-            puts stderr "no rename performed"
+            puts stderr "commandstack::rename_command no rename performed for command '$command' by '$renamer'"
+            #add something to stack?
             return [dict create implementation ""]
         }
         catch {rename ::commandstack::temp::testproc ""}