diff --git a/src/lib/cbfs.c b/src/lib/cbfs.c
index fc6e88721e..84638dab88 100644
--- a/src/lib/cbfs.c
+++ b/src/lib/cbfs.c
@@ -175,8 +175,11 @@ void *cbfs_simple_buffer_map(struct cbfs_simple_buffer *buffer,
 	      "allocated=%zd, size=%zd, last_allocate=%zd\n",
 	    offset, count, buffer->allocated, buffer->size,
 	    buffer->last_allocate);
-	if (buffer->allocated + count > buffer->size)
+	if (buffer->allocated + count > buffer->size) {
+		ERROR("simple_buffer: no room to map %zd bytes from %#zx\n",
+		      count, offset);
 		return CBFS_MEDIA_INVALID_MAP_ADDRESS;
+	}
 	if (media->read(media, address, offset, count) != count) {
 		ERROR("simple_buffer: fail to read %zd bytes from 0x%zx\n",
 		      count, offset);
diff --git a/src/vendorcode/google/chromeos/fmap.c b/src/vendorcode/google/chromeos/fmap.c
index a8425c0d10..7c1f626f82 100644
--- a/src/vendorcode/google/chromeos/fmap.c
+++ b/src/vendorcode/google/chromeos/fmap.c
@@ -51,7 +51,8 @@ const struct fmap *fmap_find(void)
 	media->close(media);
 #endif
 
-	if (memcmp(fmap, FMAP_SIGNATURE, sizeof(FMAP_SIGNATURE)-1)) {
+	if (fmap == CBFS_MEDIA_INVALID_MAP_ADDRESS ||
+	    memcmp(fmap, FMAP_SIGNATURE, sizeof(FMAP_SIGNATURE) - 1)) {
 		printk(BIOS_DEBUG, "No FMAP found at %p.\n", fmap);
 		return NULL;
 	}