diff --git a/amaranth/vendor/_lattice_ecp5.py b/amaranth/vendor/_lattice_ecp5.py
index c78e3ea..6136490 100644
--- a/amaranth/vendor/_lattice_ecp5.py
+++ b/amaranth/vendor/_lattice_ecp5.py
@@ -99,7 +99,7 @@ class FFBuffer(io.FFBuffer):
             i_inv = Signal.like(self.i)
             for bit in range(len(self.port)):
                 m.submodules[f"i_ff{bit}"] = Instance("IFS1P3DX",
-                    i_SCLK=ClockSignal(self.o_domain),
+                    i_SCLK=ClockSignal(self.i_domain),
                     i_SP=Const(1),
                     i_CD=Const(0),
                     i_D=buf.i[bit],