diff --git a/src/map.c b/src/map.c
index 6a994d4..b46ba37 100644
--- a/src/map.c
+++ b/src/map.c
@@ -2307,7 +2307,7 @@
     if (which == NULL)
 	return;
     mode = get_map_mode(&which, 0);
-    is_abbr = (int)tv_get_number(&argvars[1]);
+    is_abbr = (int)tv_get_bool(&argvars[1]);
 
     if (argvars[2].v_type != VAR_DICT)
     {