diff --git a/ext/fileinfo/libmagic/cdf.c b/ext/fileinfo/libmagic/cdf.c
index 4712e84942e..16649f193fb 100644
--- a/ext/fileinfo/libmagic/cdf.c
+++ b/ext/fileinfo/libmagic/cdf.c
@@ -365,10 +365,10 @@ cdf_read_short_sector(const cdf_stream_t *sst, void *buf, size_t offs,
 	size_t ss = CDF_SHORT_SEC_SIZE(h);
 	size_t pos = CDF_SHORT_SEC_POS(h, id);
 	assert(ss == len);
-	if (pos > CDF_SEC_SIZE(h) * sst->sst_len) {
+	if (pos + len > CDF_SEC_SIZE(h) * sst->sst_len) {
 		DPRINTF(("Out of bounds read %" SIZE_T_FORMAT "u > %"
 		    SIZE_T_FORMAT "u\n",
-		    pos, CDF_SEC_SIZE(h) * sst->sst_len));
+		    pos + len, CDF_SEC_SIZE(h) * sst->sst_len));
 		return -1;
 	}
 	(void)memcpy(((char *)buf) + offs,