diff --git a/src/if_tcl.c b/src/if_tcl.c
index 30f7d98..fe43d23 100644
--- a/src/if_tcl.c
+++ b/src/if_tcl.c
@@ -1407,7 +1407,7 @@
 
 #ifdef FEAT_EVAL
     expr = Tcl_GetStringFromObj(objv[objn], NULL);
-    str = (char *)eval_to_string((char_u *)expr, NULL);
+    str = (char *)eval_to_string((char_u *)expr, NULL, TRUE);
     if (str == NULL)
 	Tcl_SetResult(interp, _("invalid expression"), TCL_STATIC);
     else