diff --git a/src/pg/decoder.cr b/src/pg/decoder.cr
index c086d5af..1e8c9379 100644
--- a/src/pg/decoder.cr
+++ b/src/pg/decoder.cr
@@ -134,12 +134,12 @@ module PG
         # return String.new(ByteaDecoder.new.decode(io,bytesize))
         Hash(String, String?).new.tap do |hash|
           string_decoder = StringDecoder.new
-          key_count = read_u32(io)
+          key_count = read_u32(io) # 4
           key_count.times do
-            length = read_u32(io)
+            length = read_u32(io) # 4
             key = string_decoder.decode(io, length)
             length = read_u32(io)
-            if length == UInt32::MAX
+            if length == -1
               hash[key] = nil
             else
               value = string_decoder.decode(io, length)