diff --git a/nix/lib.nix b/nix/lib.nix
index 642dd510f..b3ac391f9 100644
--- a/nix/lib.nix
+++ b/nix/lib.nix
@@ -21,8 +21,9 @@ in rec {
   };
 
   # Generate a nix file from an opam file
-  opam2nix = { src, opamFile ? findOpamFile src, ... }@args:
-    pkgs.runCommandNoCC (args.pname or opamFile + ".nix") args
+  opam2nix =
+    { src, opamFile ? findOpamFile src, name ? opamFile + ".nix", ... }:
+    pkgs.runCommandNoCC name { }
     "cat ${src}/${opamFile} | ${pkgs.glibc.bin}/bin/iconv -c -f utf-8 -t ascii | ${opam-parser} > $out";
 
   # Traverse OPAM repository, producing an extension to
@@ -42,10 +43,15 @@ in rec {
             opam2nix {
               src = "${repo}/packages/${name}/${name}.${version}";
               opamFile = "opam";
-              pname = name;
-              inherit version;
+              name = "${name}.nix";
+            };
+          package = version:
+            self.callPackage (file version) {
+              extraArgs = {
+                pname = name;
+                inherit version;
+              };
             };
-          package = version: self.callPackage (file version) { };
           latest = package (latestVersion (versions name));
           others = map package (versions name);
         in latest // {
@@ -66,14 +72,13 @@ in rec {
 
   # Extension that adds callOPAMPackage to the package set
   callOPAMPackage = self: super: {
-    callOPAMPackage = src: newAttrs: overrides:
-      (self.callPackage (opam2nix (newAttrs // { inherit src; }))
-        overrides).overrideAttrs ({ buildInputs, ... }@args:
-          {
-            inherit src;
-            buildInputs = buildInputs ++ newAttrs.extraBuildInputs or [ ];
-            propagatedBuildInputs = buildInputs
-              ++ newAttrs.extraBuildInputs or [ ];
-          } // newAttrs);
+    callOPAMPackage = src: extraArgs: overrides:
+      (self.callPackage (opam2nix (extraArgs // { inherit src; }))
+      (overrides // { inherit extraArgs; })).overrideAttrs ({ buildInputs, ... }@args: {
+          inherit src;
+          buildInputs = buildInputs ++ extraArgs.extraBuildInputs or [ ];
+          propagatedBuildInputs = buildInputs
+            ++ extraArgs.extraBuildInputs or [ ];
+        });
   };
 }
diff --git a/nix/opam-parser.hs b/nix/opam-parser.hs
index b4a4d8cb3..236d7649f 100644
--- a/nix/opam-parser.hs
+++ b/nix/opam-parser.hs
@@ -38,9 +38,9 @@ opam2nix OPAM {..} =
     sepspace = mconcat . intersperse " " . normalize
     preparephase = mconcat . intersperse " " . mconcat . intersperse ["\n"]
   in
-    "{ stdenv, fetchzip, " <>deps<> " }:\n"
-  <>"with {};\n" -- Awful hack to allow this to evaluate even if some of the variables are undefined
-  <>"stdenv.mkDerivation rec {\n"
+    "{ stdenv, fetchzip, " <>deps<> ", extraArgs ? { } }:\n"
+  <>"with extraArgs;\n" -- Awful hack to allow this to evaluate even if some of the variables are undefined
+  <>"stdenv.mkDerivation (rec {\n"
   <>foldMap (\name' -> "  pname = \""<>name'<>"\";\n") name
   <>foldMap (\version' -> "  version = \""<>version'<>"\";\n") version
   <>foldMap (\url -> "  src = builtins.fetchTarball { url = \""<>url<>"\"; };\n") source
@@ -58,8 +58,7 @@ opam2nix OPAM {..} =
               <>preparephase checkPhase'
               <>"\nrunHook postCheck\n'';\n") checkPhase
   <>"  installPhase = ''\nrunHook preInstall\nopaline -prefix $out -libdir $OCAMLFIND_DESTDIR\nrunHook postInstall\n'';\n"
-
-  <>"}\n"
+  <>"} // extraArgs)\n"
 
 update :: Maybe a -> a -> Maybe a
 update old new = if isNothing old then Just new else old
@@ -196,18 +195,7 @@ listParser valueParser =
     whiteSpace = optional $ many $ oneOf " \n"
 
 main :: IO ()
-main = do
-  initialOPAM <- OPAM
-    <$> A.optional (getEnv "pname")
-    <*> A.optional (getEnv "version")
-    <*> pure Nothing
-    <*> pure Nothing
-    <*> pure Nothing
-    <*> pure Nothing
-    <*> pure Nothing
-    <*> pure Nothing
-
-  getContents >>= \s -> case parse opamFile "(unknown)" s of
+main = getContents >>= \s -> case parse opamFile "(unknown)" s of
     Left e -> print e
-    Right fs -> putStrLn $ opam2nix $ evaluateFields initialOPAM fs
+    Right fs -> putStrLn $ opam2nix $ evaluateFields (OPAM Nothing Nothing Nothing Nothing Nothing Nothing Nothing Nothing) fs
     -- Right fs -> mapM_ print fs
diff --git a/vendors/ligo-utils/memory-proto-alpha/tezos-memory-proto-alpha.opam b/vendors/ligo-utils/memory-proto-alpha/tezos-memory-proto-alpha.opam
index e6ca037cc..44ca90da2 100644
--- a/vendors/ligo-utils/memory-proto-alpha/tezos-memory-proto-alpha.opam
+++ b/vendors/ligo-utils/memory-proto-alpha/tezos-memory-proto-alpha.opam
@@ -1,5 +1,5 @@
 opam-version: "2.0"
-name: "memory-proto-alpha"
+name: "tezos-memory-proto-alpha"
 version: "1.0"
 synopsis: "Tezos Protocol Alpha in memory"
 maintainer: "Galfour <ligolang@gmail.com>"