diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 2738f4f..b52629e 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -3791,12 +3791,15 @@
     char_u   *name = argvars[0].vval.v_string;
     char_u   *p;
 
-    while (name[0] != NUL && name[0] == ':')
+    rettv->v_type = VAR_STRING;
+    rettv->vval.v_string = NULL;
+    if (name == NULL)
+	return;
+
+    while (*name != NUL && *name == ':')
 	name++;
     name = skip_range(name, TRUE, NULL);
 
-    rettv->v_type = VAR_STRING;
-
     ea.cmd = (*name == '2' || *name == '3') ? name + 1 : name;
     ea.cmdidx = (cmdidx_T)0;
     p = find_ex_command(&ea, NULL, NULL, NULL);