diff --git a/src/passwd/getgrouplist.c b/src/passwd/getgrouplist.c
index 43e51824..44785e10 100644
--- a/src/passwd/getgrouplist.c
+++ b/src/passwd/getgrouplist.c
@@ -31,12 +31,13 @@ int getgrouplist(const char *user, gid_t gid, gid_t *groups, int *ngroups)
 	if (resp[INITGRFOUND]) {
 		nscdbuf = calloc(resp[INITGRNGRPS], sizeof(uint32_t));
 		if (!nscdbuf) goto cleanup;
-		if (!fread(nscdbuf, sizeof(*nscdbuf)*resp[INITGRNGRPS], 1, f)) {
+		size_t ngrps = resp[INITGRNGRPS];
+		if (ngrps && !fread(nscdbuf, sizeof(*nscdbuf)*ngrps, 1, f)) {
 			if (!ferror(f)) errno = EIO;
 			goto cleanup;
 		}
 		if (swap) {
-			for (i = 0; i < resp[INITGRNGRPS]; i++)
+			for (i = 0; i < ngrps; i++)
 				nscdbuf[i] = bswap_32(nscdbuf[i]);
 		}
 	}