diff --git a/protobuf-simple.cabal b/protobuf-simple.cabal
--- a/protobuf-simple.cabal
+++ b/protobuf-simple.cabal
@@ -3,7 +3,7 @@
 
 name:                protobuf-simple
 synopsis:            Simple Protocol Buffers library (proto2)
-version:             0.1.0.2
+version:             0.1.0.3
 homepage:            https://github.com/sru-systems/protobuf-simple
 license:             MIT
 license-file:        LICENSE
diff --git a/src/Parser/ProtoParser.hs b/src/Parser/ProtoParser.hs
--- a/src/Parser/ProtoParser.hs
+++ b/src/Parser/ProtoParser.hs
@@ -426,7 +426,13 @@
 
 
 int32 :: Parsec String u Int32
-int32 = read <$> lexeme (many1 digit)
+int32 = read <$> lexeme ((:) <$> char '0' <*> zeroStart
+                         <|> many1 digit)
+  where
+    zeroStart = choice [ (:) <$> oneOf "xX" <*> many1 hexDigit
+                       , (:) <$> oneOf "oO" <*> many1 octDigit
+                       , many digit
+                       ]
 
 
 keyword :: String -> Parsec String u String
diff --git a/test/Parser/ProtoParserSpec.hs b/test/Parser/ProtoParserSpec.hs
--- a/test/Parser/ProtoParserSpec.hs
+++ b/test/Parser/ProtoParserSpec.hs
@@ -133,15 +133,15 @@
             , "    optional fixed32 f04 = 4;"
             , "    optional fixed64 f05 = 5;"
             , "    optional float f06 = 6;"
-            , "    optional int32 f07 = 7;"
-            , "    optional int64 f08 = 8;"
+            , "    optional int32 f07 = 0o7;"
+            , "    optional int64 f08 = 0o10;"
             , "    optional sfixed32 f09 = 9;"
             , "    optional sfixed64 f10 = 10;"
             , "    optional sint32 f11 = 11;"
             , "    optional sint64 f12 = 12;"
             , "    optional string f13 = 13;"
-            , "    optional uint32 f14 = 14;"
-            , "    optional uint64 f15 = 15;"
+            , "    optional uint32 f14 = 0xe;"
+            , "    optional uint64 f15 = 0xF;"
             , "}"
             ])
         `shouldParse`
@@ -195,11 +195,11 @@
     it "parses a message with a enum field" $
         parseProto "Test.proto" (unlines
             [ "message EnumMessage {"
-            , "    optional EnumType value = 1;"
+            , "    optional EnumType value = 0x1;"
             , "}"
             , "enum EnumType {"
             , "    UNKNOWN = 0;"
-            , "    INIT = 1;"
+            , "    INIT = 0x1;"
             , "}"
             ])
         `shouldParse`