diff --git a/notmuch-tag.c b/notmuch-tag.c
index 9a5d3e71..3b09df99 100644
--- a/notmuch-tag.c
+++ b/notmuch-tag.c
@@ -247,6 +247,11 @@ notmuch_tag_command (notmuch_config_t *config, int argc, char *argv[])
 	    fprintf (stderr, "Error: 'notmuch tag' requires at least one tag to add or remove.\n");
 	    return 1;
 	}
+
+	if (*query_string == '\0') {
+	    fprintf (stderr, "Error: notmuch tag requires at least one search term.\n");
+	    return 1;
+	}
     }
 
     if (notmuch_database_open (notmuch_config_get_database_path (config),
diff --git a/tag-util.c b/tag-util.c
index c5f58595..92e08a1d 100644
--- a/tag-util.c
+++ b/tag-util.c
@@ -190,9 +190,9 @@ parse_tag_command_line (void *ctx, int argc, char **argv,
 
     *query_str = query_string_from_args (ctx, argc - i, &argv[i]);
 
-    if (*query_str == NULL || **query_str == '\0') {
-	fprintf (stderr, "Error: notmuch tag requires at least one search term.\n");
-	return TAG_PARSE_INVALID;
+    if (*query_str == NULL) {
+	fprintf (stderr, "Out of memory.\n");
+	return TAG_PARSE_OUT_OF_MEMORY;
     }
 
     return TAG_PARSE_SUCCESS;