diff --git a/mu-protobuf.cabal b/mu-protobuf.cabal
--- a/mu-protobuf.cabal
+++ b/mu-protobuf.cabal
@@ -1,5 +1,5 @@
 name:          mu-protobuf
-version:       0.3.0.0
+version:       0.4.0.0
 synopsis:
   Protocol Buffers serialization and gRPC schema import for Mu microservices
 
@@ -32,18 +32,18 @@
 
   build-depends:
       base                    >=4.12  && <5
-    , bytestring
-    , compendium-client       >=0.3.0
-    , http-client
-    , http2-grpc-proto3-wire
-    , language-protobuf
-    , mu-rpc                  >=0.3.0
-    , mu-schema               >=0.3.0
-    , proto3-wire
-    , servant-client-core
-    , sop-core
-    , template-haskell        >=2.12
-    , text
+    , bytestring              >=0.10  && <0.11
+    , compendium-client       ==0.2.*
+    , http-client             >=0.6   && <0.7
+    , http2-grpc-proto3-wire  >=0.1   && <0.2
+    , language-protobuf       >=1.0.1 && <2
+    , mu-rpc                  ==0.4.*
+    , mu-schema               ==0.3.*
+    , proto3-wire             >=1.1   && < 2
+    , servant-client-core     >=0.16  && <0.19
+    , sop-core                >=0.5   && <0.6
+    , template-haskell        >=2.14  && <2.16
+    , text                    >=1.2   && <2
 
   hs-source-dirs:   src
   default-language: Haskell2010
@@ -54,7 +54,7 @@
   build-depends:
       base         >=4.12  && <5
     , bytestring
-    , mu-protobuf  >=0.3.0
+    , mu-protobuf
     , mu-schema    >=0.3.0
     , proto3-wire
     , text
diff --git a/src/Mu/Adapter/ProtoBuf.hs b/src/Mu/Adapter/ProtoBuf.hs
--- a/src/Mu/Adapter/ProtoBuf.hs
+++ b/src/Mu/Adapter/ProtoBuf.hs
@@ -26,6 +26,7 @@
 module Mu.Adapter.ProtoBuf (
   -- * Custom annotations
   ProtoBufAnnotation(..)
+, ProtoBufOptionConstant(..)
   -- * Conversion using schemas
 , IsProtoSchema
 , toProtoViaSchema
@@ -62,16 +63,23 @@
 data ProtoBufAnnotation
   = -- | Numeric field identifier for normal fields
     --   and whether it should be packed (only used for lists of number-like values)
-    ProtoBufId Nat Bool
+    ProtoBufId Nat [(Symbol, ProtoBufOptionConstant)]
     -- | List of identifiers for fields which contain a union
   | ProtoBufOneOfIds [Nat]
 
+-- Values for constants
+data ProtoBufOptionConstant
+  = ProtoBufOptionConstantInt    Nat
+  | ProtoBufOptionConstantBool   Bool
+  | ProtoBufOptionConstantObject [(Symbol, ProtoBufOptionConstant)]
+  | ProtoBufOptionConstantOther  Symbol
+
 type family FindProtoBufId (sch :: Schema tn fn) (t :: tn) (f :: fn) where
   FindProtoBufId sch t f
     = FindProtoBufId' t f (GetFieldAnnotation (AnnotatedSchema ProtoBufAnnotation sch) t f)
 
 type family FindProtoBufId' (t :: tn) (f :: fn) (p :: ProtoBufAnnotation) :: Nat where
-  FindProtoBufId' t f ('ProtoBufId n b) = n
+  FindProtoBufId' t f ('ProtoBufId n opts) = n
   FindProtoBufId' t f other
     = TypeError ('Text "protocol buffers id not available for field "
                  ':<>: 'ShowType t ':<>: 'Text "/" ':<>: 'ShowType f)
@@ -81,10 +89,21 @@
     = FindProtoBufPacked' t f (GetFieldAnnotation (AnnotatedSchema ProtoBufAnnotation sch) t f)
 
 type family FindProtoBufPacked' (t :: tn) (f :: fn) (p :: ProtoBufAnnotation) :: Bool where
-  FindProtoBufPacked' t f ('ProtoBufId n b) = b
+  FindProtoBufPacked' t f ('ProtoBufId n opts)
+    = FindProtoBufPacked'' t f opts
   FindProtoBufPacked' t f other
     = TypeError ('Text "protocol buffers id not available for field "
                  ':<>: 'ShowType t ':<>: 'Text "/" ':<>: 'ShowType f)
+
+type family FindProtoBufPacked'' (t :: tn) (f :: fn) (opts :: [(Symbol, ProtoBufOptionConstant)]) :: Bool where
+  FindProtoBufPacked'' t f '[] = 'True  -- by default we are packed
+  FindProtoBufPacked'' t f ( '("packed", 'ProtoBufOptionConstantBool b) ': rest )
+    = b  -- found!
+  FindProtoBufPacked'' t f ( '("packed", other) ': rest )
+    = TypeError ('Text "non-boolean value for 'packed' for field "
+                 ':<>: 'ShowType t ':<>: 'Text "/" ':<>: 'ShowType f)
+  FindProtoBufPacked'' t f ( other ': rest)
+    = FindProtoBufPacked'' t f rest
 
 type family FindProtoBufOneOfIds (sch :: Schema tn fn) (t :: tn) (f :: fn) where
   FindProtoBufOneOfIds sch t f
diff --git a/src/Mu/Quasi/GRpc.hs b/src/Mu/Quasi/GRpc.hs
--- a/src/Mu/Quasi/GRpc.hs
+++ b/src/Mu/Quasi/GRpc.hs
@@ -1,4 +1,5 @@
 {-# language DataKinds         #-}
+{-# language KindSignatures    #-}
 {-# language OverloadedStrings #-}
 {-# language TemplateHaskell   #-}
 {-|
@@ -16,6 +17,7 @@
 
 import           Control.Monad.IO.Class
 import qualified Data.Text                       as T
+import           GHC.TypeLits
 import           Language.Haskell.TH
 import           Language.ProtocolBuffers.Parser
 import qualified Language.ProtocolBuffers.Types  as P
@@ -70,23 +72,23 @@
 pbServiceDeclToType :: Maybe [T.Text] -> Name -> P.ServiceDeclaration -> Q Type
 pbServiceDeclToType pkg schema (P.Service nm _ methods)
   = [t| 'Package $(pkgType pkg)
-          '[ 'Service $(textToStrLit nm) '[]
+          '[ 'Service $(textToStrLit nm)
                       $(typesToList <$> mapM (pbMethodToType schema) methods) ] |]
   where
-    pkgType Nothing  = [t| 'Nothing |]
+    pkgType Nothing  = [t| ('Nothing :: Maybe Symbol) |]
     pkgType (Just p) = [t| 'Just $(textToStrLit (T.intercalate "." p)) |]
 
 pbMethodToType :: Name -> P.Method -> Q Type
 pbMethodToType s (P.Method nm vr v rr r _)
-  = [t| 'Method $(textToStrLit nm) '[]
+  = [t| 'Method $(textToStrLit nm)
                 $(argToType vr v) $(retToType rr r) |]
   where
     argToType P.Single (P.TOther ["google","protobuf","Empty"])
       = [t| '[ ] |]
     argToType P.Single (P.TOther a)
-      = [t| '[ 'ArgSingle 'Nothing '[] ('SchemaRef $(schemaTy s) $(textToStrLit (last a))) ] |]
+      = [t| '[ 'ArgSingle ('Nothing :: Maybe Symbol) ('SchemaRef $(schemaTy s) $(textToStrLit (last a))) ] |]
     argToType P.Stream (P.TOther a)
-      = [t| '[ 'ArgStream 'Nothing '[] ('SchemaRef $(schemaTy s) $(textToStrLit (last a))) ] |]
+      = [t| '[ 'ArgStream ('Nothing :: Maybe Symbol) ('SchemaRef $(schemaTy s) $(textToStrLit (last a))) ] |]
     argToType _ _
       = fail "only message types may be used as arguments"
 
@@ -104,7 +106,7 @@
 
 typesToList :: [Type] -> Type
 typesToList
-  = foldr (\y ys -> AppT (AppT PromotedConsT y) ys) PromotedNilT
+  = foldr (AppT . AppT PromotedConsT) PromotedNilT
 textToStrLit :: T.Text -> Q Type
 textToStrLit s
   = pure $ LitT $ StrTyLit $ T.unpack s
diff --git a/src/Mu/Quasi/ProtoBuf.hs b/src/Mu/Quasi/ProtoBuf.hs
--- a/src/Mu/Quasi/ProtoBuf.hs
+++ b/src/Mu/Quasi/ProtoBuf.hs
@@ -18,6 +18,7 @@
   , protobufToDecls
   ) where
 
+import           Control.Monad                   (when)
 import           Control.Monad.IO.Class
 import qualified Data.ByteString                 as B
 import           Data.Int
@@ -79,7 +80,7 @@
     pbChoiceToType :: P.EnumField -> Q (Type, Type)
     pbChoiceToType (P.EnumField nm number _)
       = (,) <$> [t|'ChoiceDef $(textToStrLit nm) |]
-            <*> [t|'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit number) 'True) |]
+            <*> [t|'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit number) '[]) |]
 pbTypeDeclToType (P.DMessage name _ _ fields _) = do
   (tys, anns) <- unzip <$> mapM pbMsgFieldToType fields
   (,) <$> [t|'DRecord $(textToStrLit name) $(pure $ typesToList tys)|] <*> pure anns
@@ -89,23 +90,23 @@
     -- it's possible to distinguish whether it's missing on wire
     -- or should be set to the default, so use Option
     -- +info -> https://github.com/higherkindness/mu-haskell/pull/130#issuecomment-596433307
-    pbMsgFieldToType (P.NormalField P.Single ty@(P.TOther _) nm n opts)
-      = (,) <$> [t| 'FieldDef $(textToStrLit nm) ('TOption $(pbFieldTypeToType ty)) |]
-            <*> [t| 'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit n) $(pbOptionsToPacked opts)) |]
-    pbMsgFieldToType (P.NormalField P.Single ty nm n opts)
-      = (,) <$> [t| 'FieldDef $(textToStrLit nm) $(pbFieldTypeToType ty) |]
-            <*> [t| 'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit n) $(pbOptionsToPacked opts)) |]
-    pbMsgFieldToType (P.NormalField P.Repeated ty nm n opts)
-      = (,) <$> [t| 'FieldDef $(textToStrLit nm) ('TList $(pbFieldTypeToType ty)) |]
-            <*> [t| 'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit n) $(pbOptionsToPacked opts)) |]
-    pbMsgFieldToType (P.MapField k v nm n opts)
-      = (,) <$> [t| 'FieldDef $(textToStrLit nm) ('TMap $(pbFieldTypeToType k) $(pbFieldTypeToType v)) |]
-            <*> [t| 'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit n) $(pbOptionsToPacked opts)) |]
+    pbMsgFieldToType (P.NormalField P.Single ty@(P.TOther _) nm n opts) =
+        (,) <$> [t| 'FieldDef $(textToStrLit nm) ('TOption $(pbFieldTypeToType ty)) |]
+            <*> [t| 'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit n) $(typesToList <$> mapM pbOption opts)) |]
+    pbMsgFieldToType (P.NormalField P.Single ty nm n opts) =
+        (,) <$> [t| 'FieldDef $(textToStrLit nm) $(pbFieldTypeToType ty) |]
+            <*> [t| 'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit n) $(typesToList <$> mapM pbOption opts)) |]
+    pbMsgFieldToType (P.NormalField P.Repeated ty nm n opts) =
+        (,) <$> [t| 'FieldDef $(textToStrLit nm) ('TList $(pbFieldTypeToType ty)) |]
+            <*> [t| 'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit n) $(typesToList <$> mapM pbOption opts)) |]
+    pbMsgFieldToType (P.MapField k v nm n opts) =
+        (,) <$> [t| 'FieldDef $(textToStrLit nm) ('TMap $(pbFieldTypeToType k) $(pbFieldTypeToType v)) |]
+            <*> [t| 'AnnField $(textToStrLit name) $(textToStrLit nm) ('ProtoBufId $(intToLit n) $(typesToList <$> mapM pbOption opts)) |]
     pbMsgFieldToType (P.OneOfField nm vs)
-      | any (not . hasFieldNumber) vs
+      | not (all hasFieldNumber vs)
       = fail "nested oneof fields are not supported"
       | otherwise
-      = (,) <$> [t| 'FieldDef $(textToStrLit nm) $(typesToList <$> mapM pbOneOfFieldToType vs ) |]
+      = (,) <$> [t| 'FieldDef $(textToStrLit nm) ('TUnion $(typesToList <$> mapM pbOneOfFieldToType vs )) |]
             <*> [t| 'AnnField $(textToStrLit name) $(textToStrLit nm)
                        ('ProtoBufOneOfIds $(typesToList <$> mapM (intToLit . getFieldNumber) vs )) |]
 
@@ -142,17 +143,30 @@
       = [t| 'TMap $(pbFieldTypeToType k) $(pbFieldTypeToType v) |]
     pbOneOfFieldToType _ = error "this should never happen"
 
-    pbOptionsToPacked []
-      = [t| 'True |]
-    pbOptionsToPacked (P.Option ["packed"] val : _)
-      | P.KBool True  <- val = [t| 'True  |]
-      | P.KBool False <- val = [t| 'False |]
-      | otherwise = fail "'packed' with a non-boolean value"
-    pbOptionsToPacked (_ : rest)
-      = pbOptionsToPacked rest
+    pbOption (P.Option oname val)
+      = do when (oname == ["default"])
+                (reportError "mu-protobuf does not (yet) support default values")
+           [t| '( $(textToStrLit (T.intercalate "." oname))
+                , $(pbConstantToOption val) ) |]
 
+    pbConstantToOption (P.KIdentifier names)
+      = [t| 'ProtoBufOptionConstantOther $(textToStrLit (T.intercalate "." names)) |]
+    pbConstantToOption (P.KInt n)
+      = [t| 'ProtoBufOptionConstantInt $(intToLit (fromInteger n)) |]
+    pbConstantToOption (P.KBool True)
+      = [t| 'ProtoBufOptionConstantBool 'True |]
+    pbConstantToOption (P.KBool False)
+      = [t| 'ProtoBufOptionConstantBool 'False |]
+    pbConstantToOption (P.KString s)
+      = [t| 'ProtoBufOptionConstantOther $(textToStrLit s) |]
+    pbConstantToOption (P.KFloat s)
+      = [t| 'ProtoBufOptionConstantOther $(textToStrLit (T.pack (show s))) |]
+    pbConstantToOption (P.KObject s)
+      = [t| 'ProtoBufOptionConstantObject
+            $(typesToList <$> mapM (\(n, o) -> [t| '( $(textToStrLit n), $(pbConstantToOption o) ) |] ) s ) |]
+
 typesToList :: [Type] -> Type
-typesToList = foldr (\y ys -> AppT (AppT PromotedConsT y) ys) PromotedNilT
+typesToList = foldr (AppT . AppT PromotedConsT) PromotedNilT
 
 textToStrLit :: T.Text -> Q Type
 textToStrLit s = pure $ LitT $ StrTyLit $ T.unpack s
diff --git a/test/ProtoBuf.hs b/test/ProtoBuf.hs
--- a/test/ProtoBuf.hs
+++ b/test/ProtoBuf.hs
@@ -39,17 +39,17 @@
   deriving (FromSchema ExampleSchema "address")
 
 type instance AnnotatedSchema ProtoBufAnnotation ExampleSchema
-  = '[ 'AnnField "gender" "male"   ('ProtoBufId 1 'True)
-     , 'AnnField "gender" "female" ('ProtoBufId 2 'True)
-     , 'AnnField "gender" "nb"     ('ProtoBufId 3 'True)
-     , 'AnnField "address" "postcode" ('ProtoBufId 1 'True)
-     , 'AnnField "address" "country"  ('ProtoBufId 2 'True)
-     , 'AnnField "person" "firstName" ('ProtoBufId 1 'True)
-     , 'AnnField "person" "lastName"  ('ProtoBufId 2 'True)
-     , 'AnnField "person" "age"       ('ProtoBufId 3 'True)
-     , 'AnnField "person" "gender"    ('ProtoBufId 4 'True)
-     , 'AnnField "person" "address"   ('ProtoBufId 5 'True)
-     , 'AnnField "person" "lucky_numbers" ('ProtoBufId 6 'True) ]
+  = '[ 'AnnField "gender" "male"   ('ProtoBufId 1 '[])
+     , 'AnnField "gender" "female" ('ProtoBufId 2 '[])
+     , 'AnnField "gender" "nb"     ('ProtoBufId 3 '[])
+     , 'AnnField "address" "postcode" ('ProtoBufId 1 '[])
+     , 'AnnField "address" "country"  ('ProtoBufId 2 '[])
+     , 'AnnField "person" "firstName" ('ProtoBufId 1 '[])
+     , 'AnnField "person" "lastName"  ('ProtoBufId 2 '[])
+     , 'AnnField "person" "age"       ('ProtoBufId 3 '[])
+     , 'AnnField "person" "gender"    ('ProtoBufId 4 '[])
+     , 'AnnField "person" "address"   ('ProtoBufId 5 '[])
+     , 'AnnField "person" "lucky_numbers" ('ProtoBufId 6 '[ '("packed", 'ProtoBufOptionConstantBool 'True) ]) ]
 
 exampleAddress :: MAddress
 exampleAddress = MAddress "1111BB" "Spain"