diff --git a/fmap.c b/fmap.c
index d44b7fa..84b3b54 100644
--- a/fmap.c
+++ b/fmap.c
@@ -243,7 +243,7 @@
 			if (flashctx->chip->read(flashctx, (uint8_t *)fmap + sig_len,
 						offset + sig_len, sizeof(*fmap) - sig_len)) {
 				msg_cerr("Cannot read %zu bytes at offset %06zx\n",
-						sizeof(*fmap) + sig_len, offset + sig_len);
+						sizeof(*fmap) - sig_len, offset + sig_len);
 				continue;
 			}