diff --git a/CHANGES b/CHANGES
index 69f9853..9d0acd7 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,9 @@
 i2c-tools CHANGES
 -----------------
 
+3.1.3 (work in progress)
+  decode-dimms: Correctly check for out-of-bounds vendor ID
+
 3.1.2 (2015-06-17)
   decode-dimms: Fix DDR3 extended temp range refresh rate decoding
   py-smbus: Add support for python 3
diff --git a/eeprom/decode-dimms b/eeprom/decode-dimms
index a088ba0..4a15fd7 100755
--- a/eeprom/decode-dimms
+++ b/eeprom/decode-dimms
@@ -343,9 +343,11 @@ sub manufacturer_ddr3($$)
 {
 	my ($count, $code) = @_;
 	return "Invalid" if parity($count) != 1;
-	return "Invalid" if parity($code) != 1;
-	return (($code & 0x7F) - 1 > $vendors[$count & 0x7F]) ? "Unknown" :
-		$vendors[$count & 0x7F][($code & 0x7F) - 1];
+	return "Invalid" if parity($code) != 1
+			 or ($code & 0x7F) == 0;
+	return "Unknown" if ($count & 0x7F) >= @vendors
+			 or ($code & 0x7F) - 1 >= @{$vendors[$count & 0x7F]};
+	return $vendors[$count & 0x7F][($code & 0x7F) - 1];
 }
 
 sub manufacturer(@)