diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4bd0fee3..f3917d68 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -150,7 +150,7 @@ jobs:
 
     - name: Flash bitstream
       run: |
-        nix run .#bitstream-load
+        DEVICE=/dev/ttySONATA_JTAG_FPGA nix run .#bitstream-load
 
     - name: Run software tests
       run: |
diff --git a/nix/bitstream.nix b/nix/bitstream.nix
index 8d059566..c781f3bc 100644
--- a/nix/bitstream.nix
+++ b/nix/bitstream.nix
@@ -61,7 +61,11 @@ in {
     runtimeInputs = [pythonEnv pkgs.openfpgaloader];
     text = ''
       BITSTREAM=$(find ./ -type f -name "lowrisc_sonata_system_0.bit")
-      openFPGALoader -c ft4232 "$BITSTREAM"
+      if [[ -n "''${DEVICE-}" ]]; then
+        openFPGALoader -c ft4232 -d "$DEVICE" "$BITSTREAM"
+      else
+        openFPGALoader -c ft4232 "$BITSTREAM"
+      fi
     '';
   };
 }