1 file changed, 4 insertions, 1 deletion
diff --git a/source/ui-tag.c b/source/ui-tag.c
index 656280e..7020ed7 100644
--- a/source/ui-tag.c
+++ b/source/ui-tag.c
@@ -82,7 +82,10 @@ static void print_annotated_tag(const char *revname,
 	}
 	if (info->tagger) {
 		html("<tr><th>tagged by</th><td>");
-		cgit_open_filter(ctx.repo->email_filter, info->tagger_email,
+		// A tag can carry a tagger with no address, and a filter must
+		// not be handed a NULL argument.
+		cgit_open_filter(ctx.repo->email_filter,
+				 info->tagger_email ? info->tagger_email : "",
 				 "tag");
 		html_txt(info->tagger);
 		if (info->tagger_email && !ctx.cfg.noplainemail) {