diff --git a/artiq/coredevice/ttl.py b/artiq/coredevice/ttl.py
index 45c3d6fe9..9143dc7c9 100644
--- a/artiq/coredevice/ttl.py
+++ b/artiq/coredevice/ttl.py
@@ -482,16 +482,14 @@ class TTLClockGen:
         """Returns the frequency tuning word corresponding to the given
         frequency.
         """
-        # NAC3TODO return round64(2**self.acc_width*frequency*self.core.coarse_ref_period)
-        return 0
+        return round(2.**float(self.acc_width)*frequency*self.core.coarse_ref_period)
 
     @portable
     def ftw_to_frequency(self, ftw: int32) -> float:
         """Returns the frequency corresponding to the given frequency tuning
         word.
         """
-        # NAC3TODO return float(ftw)/self.core.coarse_ref_period/2**int64(self.acc_width)
-        return 0.0
+        return float(ftw)/self.core.coarse_ref_period/2.**float(self.acc_width)
 
     @kernel
     def set_mu(self, frequency: int32):
diff --git a/flake.lock b/flake.lock
index 4dff9bbdd..4d6488c01 100644
--- a/flake.lock
+++ b/flake.lock
@@ -80,11 +80,11 @@
         "nixpkgs": "nixpkgs"
       },
       "locked": {
-        "lastModified": 1641304829,
-        "narHash": "sha256-bXD7l+MMCgUzHPGybsF3poDLU5B8QLpbmuXecIOtMbk=",
+        "lastModified": 1641699066,
+        "narHash": "sha256-tjcdd8h9Jy1JzZKPjCVGYJtC4sXLmteMrpVeXs0Cff4=",
         "ref": "master",
-        "rev": "52ccf31bb17f804f2700eb88de4ddc61e9a38476",
-        "revCount": 536,
+        "rev": "8ef9e74aaf0e548d4b636a1d1c1cb208b26b04c1",
+        "revCount": 544,
         "type": "git",
         "url": "https://git.m-labs.hk/M-Labs/nac3.git"
       },