diff --git a/nix/t1/mill-modules.nix b/nix/t1/mill-modules.nix
index b7f95811d..a569d0366 100644
--- a/nix/t1/mill-modules.nix
+++ b/nix/t1/mill-modules.nix
@@ -73,7 +73,10 @@ let
       dependencies.setupHook
     ];
 
-    env.CIRCT_INSTALL_PATH = circt-full;
+    env = {
+      CIRCT_INSTALL_PATH = circt-full;
+      JEXTRACT_INSTALL_PATH = jextract-21;
+    };
 
     outputs = [ "out" "configgen" "elaborator" "t1package" ];
 
diff --git a/nix/t1/omreader.nix b/nix/t1/omreader.nix
index b51457f92..ba4ef3bfb 100644
--- a/nix/t1/omreader.nix
+++ b/nix/t1/omreader.nix
@@ -76,6 +76,7 @@ let
     ];
 
     env = {
+      JEXTRACT_INSTALL_PATH = jextract-21;
       CIRCT_INSTALL_PATH = circt-full;
       JAVA_TOOL_OPTIONS = "--enable-preview";
     };