diff --git a/main.c b/main.c
index 558ee8b..cedf44e 100644
--- a/main.c
+++ b/main.c
@@ -136,19 +136,21 @@ static uint16_t edid_length(const uint8_t* edid)
 
 	if (1 == edid[18]) { // EDID 1.3/1.4 128-byte structure
 		if (checksum_ok(&edid[0], 128)) { // ensure checksum of base EDID is ok
-			const uint16_t length = 128 + (1 + edid[126]) * 128; // get length with all extensions
-			puts("(v1.4 ");
+			const uint16_t length = 128 + edid[126] * 128; // get length with all extensions
+			puts("(v1.3/1.4, ");
 			putn(edid[126]  / 100);
 			putn((edid[126]  / 10) % 10);
 			putn(edid[126] % 10);
 			puts(" extension) ");
-			for (uint16_t i = 128; i < length && i < 256; i += 128) { // verify checksum of each extension (we actually only support one extension)
-				if (!checksum_ok(&edid[i], 128)) {
-					puts("extension CRC error\r\n");
-					return 0; // EDID is broken
+			if (edid[126]) { // extensions are present
+				for (uint16_t i = 128; i < length && i < 256; i += 128) { // verify checksum of each extension (we actually only support one extension)
+					if (!checksum_ok(&edid[i], 128)) {
+						puts("extension CRC error\r\n");
+						return 0; // EDID is broken
+					}
 				}
 			}
-			puts("CRC ok\r\n");
+			puts("CRC OK\r\n");
 			return length;
 		} else {
 			puts("base CRC error\r\n");