diff --git a/src/passwd/getgrent_a.c b/src/passwd/getgrent_a.c
index ccb51d5..b099786 100644
--- a/src/passwd/getgrent_a.c
+++ b/src/passwd/getgrent_a.c
@@ -31,7 +31,7 @@ struct group *__getgrent_a(FILE *f, struct group *gr, char **line, size_t *size,
 	for (*nmem=!!*s; *s; s++)
 		if (*s==',') ++*nmem;
 	free(*mem);
-	*mem = calloc(sizeof(char *), *nmem+1);
+	*mem = calloc(**mem, *nmem+2);
 	if (!*mem) {
 		free(*line);
 		*line = 0;