diff --git a/nix/t1/default.nix b/nix/t1/default.nix
index 6be4711aa4..cc6958c72f 100644
--- a/nix/t1/default.nix
+++ b/nix/t1/default.nix
@@ -25,9 +25,9 @@ lib.makeScope newScope
 
     elaborator = _millOutput.elaborator // { meta.mainProgram = "elaborator"; };
     configgen = _millOutput.configgen // { meta.mainProgram = "configgen"; };
-    omreader = _millOutput.omreader // { meta.mainProgram = "omreader"; };
     t1package = _millOutput.t1package;
 
+    omreader = self.callPackage ./omreader.nix { };
     submodules = self.callPackage ./submodules.nix { };
 
     riscv-opcodes-src = self.submodules.sources.riscv-opcodes.src;
diff --git a/nix/t1/om.nix b/nix/t1/om.nix
index 8c4361df5d..eb76a5a3fe 100644
--- a/nix/t1/om.nix
+++ b/nix/t1/om.nix
@@ -15,10 +15,10 @@ in
 stdenvNoCC.mkDerivation {
   name = "t1-${mlirbc.elaborateConfig}-${mlirbc.elaborateTarget}-om";
 
-  nativeBuildInputs = [ circt ];
+  nativeBuildInputs = [ circt omreader ];
 
   buildCommand = ''
-    ${omreader}/bin/omreader ${lib.escapeShellArgs omReaderArgs}
+    omreader ${lib.escapeShellArgs omReaderArgs}
   '';
 
   meta.description = "TODO.";
diff --git a/nix/t1/omreader.nix b/nix/t1/omreader.nix
new file mode 100644
index 0000000000..e8e4db402b
--- /dev/null
+++ b/nix/t1/omreader.nix
@@ -0,0 +1,88 @@
+{ lib
+, stdenv
+, fetchMillDeps
+, makeWrapper
+
+  # chisel deps
+, mill
+, espresso
+, circt-full
+, jextract
+, strip-nondeterminism
+
+, submodules
+}:
+
+let
+  self = stdenv.mkDerivation rec {
+    name = "omreader";
+
+    src = with lib.fileset; toSource {
+      root = ./../..;
+      fileset = unions [
+        ./../../build.sc
+        ./../../common.sc
+        ./../../omreader
+        ./../../omreaderlib
+      ];
+    };
+
+    passthru.millDeps = fetchMillDeps {
+      inherit name;
+      src = with lib.fileset; toSource {
+        root = ./../..;
+        fileset = unions [
+          ./../../build.sc
+          ./../../common.sc
+        ];
+      };
+      millDepsHash = "sha256-rkS/bTDnjnyzdQyTIhfLj3e0mMdDn4fzv/660rO3qYg=";
+      nativeBuildInputs = [ submodules.setupHook ];
+    };
+
+    passthru.editable = self.overrideAttrs (_: {
+      shellHook = ''
+        setupSubmodulesEditable
+        mill mill.bsp.BSP/install 0
+      '';
+    });
+
+    shellHook = ''
+      setupSubmodules
+    '';
+
+    nativeBuildInputs = [
+      mill
+      jextract
+      strip-nondeterminism
+      circt-full
+
+      makeWrapper
+      passthru.millDeps.setupHook
+
+      submodules.setupHook
+    ];
+
+    env = {
+      CIRCT_INSTALL_PATH = circt-full;
+      JAVA_TOOL_OPTIONS = "--enable-preview";
+    };
+
+    buildPhase = ''
+      mill -i 'omreader.assembly'
+    '';
+
+    installPhase = ''
+      mkdir -p "$out"/bin "$out"/share/java
+      strip-nondeterminism out/omreader/assembly.dest/out.jar
+      mv out/omreader/assembly.dest/out.jar "$out"/share/java/omreader.jar
+      makeWrapper ${mill.jre}/bin/java "$out"/bin/omreader --add-flags "--enable-preview -Djava.library.path=${circt-full}/lib -jar $out/share/java/omreader.jar"
+    '';
+
+    meta = {
+      description = "omreader";
+      mainProgram = "omreader";
+    };
+  };
+in
+self
diff --git a/nix/t1/t1.nix b/nix/t1/t1.nix
index 581c88a28f..5e7c240626 100644
--- a/nix/t1/t1.nix
+++ b/nix/t1/t1.nix
@@ -31,6 +31,7 @@ let
         ./../../elaborator
         ./../../configgen
         ./../../omreader
+        ./../../omreaderlib
       ];
     };
 
@@ -72,7 +73,7 @@ let
 
     env.CIRCT_INSTALL_PATH = circt-full;
 
-    outputs = [ "out" "configgen" "elaborator" "t1package" "omreader" ];
+    outputs = [ "out" "configgen" "elaborator" "t1package" ];
 
     buildPhase = ''
       mill -i '__.assembly'
@@ -86,24 +87,21 @@ let
 
       strip-nondeterminism out/elaborator/assembly.dest/out.jar
       strip-nondeterminism out/configgen/assembly.dest/out.jar
-      strip-nondeterminism out/omreader/assembly.dest/out.jar
       strip-nondeterminism out/t1package/assembly.dest/out.jar
       strip-nondeterminism out/t1package/sourceJar.dest/out.jar
       strip-nondeterminism out/t1package/chiselPluginJar.dest/out.jar
 
       mv out/configgen/assembly.dest/out.jar $out/share/java/configgen.jar
       mv out/elaborator/assembly.dest/out.jar $out/share/java/elaborator.jar
-      mv out/omreader/assembly.dest/out.jar $out/share/java/omreader.jar
 
       mkdir -p $t1package/share/java
       mv out/t1package/sourceJar.dest/out.jar $t1package/share/java/t1package-sources.jar
       mv out/t1package/assembly.dest/out.jar $t1package/share/java/t1package.jar
       mv out/t1package/chiselPluginJar.dest/out.jar $t1package/share/java/chiselPluginJar.jar
 
-      mkdir -p $configgen/bin $elaborator/bin $omreader/bin
+      mkdir -p $configgen/bin $elaborator/bin
       makeWrapper ${jdk21}/bin/java $configgen/bin/configgen --add-flags "-jar $out/share/java/configgen.jar"
       makeWrapper ${jdk21}/bin/java $elaborator/bin/elaborator --add-flags "--enable-preview -Djava.library.path=${circt-full}/lib -jar $out/share/java/elaborator.jar"
-      makeWrapper ${jdk21}/bin/java $omreader/bin/omreader --add-flags "--enable-preview -Djava.library.path=${circt-full}/lib -jar $out/share/java/omreader.jar"
     '';
   };
 in
diff --git a/omreaderlib/Interface.scala b/omreaderlib/src/Interface.scala
similarity index 100%
rename from omreaderlib/Interface.scala
rename to omreaderlib/src/Interface.scala