diff --git a/passes/sat/clk2fflogic.cc b/passes/sat/clk2fflogic.cc
index 2c0e13f85..bcefa7d8f 100644
--- a/passes/sat/clk2fflogic.cc
+++ b/passes/sat/clk2fflogic.cc
@@ -238,7 +238,8 @@ struct Clk2fflogicPass : public Pass {
 						cell->setPort(ID::EN, module->And(NEW_ID, sig_en_sampled, sig_trg_combined));
 						cell->setPort(ID::ARGS, sig_args_sampled);
 						if (cell->type == ID($check)) {
-							SigBit sig_a_sampled = sample_data(module, sig_en, State::S1, false, false).sampled;
+							SigBit sig_a = cell->getPort(ID::A);
+							SigBit sig_a_sampled = sample_data(module, sig_a, State::S1, false, false).sampled;
 							cell->setPort(ID::A, sig_a_sampled);
 						}
 					}
diff --git a/tests/various/clk2fflogic_effects.sh b/tests/various/clk2fflogic_effects.sh
index f44afc1dd..0d133ffdd 100755
--- a/tests/various/clk2fflogic_effects.sh
+++ b/tests/various/clk2fflogic_effects.sh
@@ -1,27 +1,35 @@
 #!/usr/bin/env bash
-set -ex
+set -e
 
-../../yosys -p "
-read_verilog -formal -DFAST clk2fflogic_effects.sv
+# TODO: when sim gets native $check support, remove the -DNO_ASSERT here
+echo Running yosys sim
+../../yosys -q -p "
+read_verilog -formal -DNO_ASSERT clk2fflogic_effects.sv
 hierarchy -top top; proc;;
-tee -o clk2fflogic_effects.sim.log sim -fst clk2fflogic_effects.sim.fst -q -n 16
-"
 
-../../yosys -p "
-read_verilog -formal -DFAST clk2fflogic_effects.sv
+tee -q -o clk2fflogic_effects.sim.log sim -q -n 32
+"
+echo Running yosys clk2fflogic sim
+../../yosys -q -p "
+read_verilog -formal clk2fflogic_effects.sv
 hierarchy -top top; proc;;
 clk2fflogic;;
 
-tee -o clk2fflogic_effects.clk2fflogic.log sim -fst clk2fflogic_effects.clk2fflogic.fst -q -n 16
+logger -nowarn ^Assertion
+tee -q -o clk2fflogic_effects.clk2fflogic.log sim -q -n 32
 "
 
-iverilog -g2012 -o clk2fflogic_effects.iv.out clk2fflogic_effects.sv
+echo Running iverilog sim
+iverilog -g2012 -DNO_ASSERT -o clk2fflogic_effects.iv.out clk2fflogic_effects.sv
+
 
 ./clk2fflogic_effects.iv.out > clk2fflogic_effects.iv.log
 
-sort clk2fflogic_effects.iv.log > clk2fflogic_effects.iv.sorted.log
-tail -n +3 clk2fflogic_effects.sim.log | sort > clk2fflogic_effects.sim.sorted.log
-tail -n +3 clk2fflogic_effects.clk2fflogic.log | sort > clk2fflogic_effects.clk2fflogic.sorted.log
+gawk '/([0-9]+):/{T=$1;print};/^Failed/{print T,$0}' clk2fflogic_effects.iv.log | sort > clk2fflogic_effects.iv.sorted.log
+gawk '/([0-9]+):/{T=$1;print};/^Failed/{print T,$0}' clk2fflogic_effects.sim.log | sort > clk2fflogic_effects.sim.sorted.log
+gawk '/([0-9]+):/{T=$1;print};/^Failed/{print T,$0}' clk2fflogic_effects.clk2fflogic.log | sort > clk2fflogic_effects.clk2fflogic.sorted.log
 
+echo Comparing iverilog sim vs yosys sim
 cmp clk2fflogic_effects.iv.sorted.log clk2fflogic_effects.sim.sorted.log
+echo Comparing iverilog sim vs yosys clk2fflogic sim
 cmp clk2fflogic_effects.iv.sorted.log clk2fflogic_effects.clk2fflogic.sorted.log
diff --git a/tests/various/clk2fflogic_effects.sv b/tests/various/clk2fflogic_effects.sv
index b571cf3fe..b38aba3c9 100644
--- a/tests/various/clk2fflogic_effects.sv
+++ b/tests/various/clk2fflogic_effects.sv
@@ -7,7 +7,7 @@ reg clk = 0;
 always @(posedge gclk)
     clk <= !clk;
 
-reg [4:0] counter = 0;
+reg [5:0] counter = 0;
 
 reg eff_0_trg = '0;
 reg eff_0_en = '0;
@@ -20,6 +20,10 @@ reg eff_2_trgA = '0;
 reg eff_2_trgB = '0;
 reg eff_2_en = '0;
 
+reg eff_3_trg = '0;
+reg eff_3_en = '0;
+reg eff_3_a = '0;
+
 `ifdef FAST
 always @(posedge gclk) begin
 `else
@@ -37,6 +41,10 @@ always @(posedge clk) begin
     eff_2_trgA = counter[0];
     eff_2_trgB = !counter[0];
     eff_2_en  <= 32'b00000000000000000000001111111100 >> counter;
+
+    eff_3_trg  = 32'b10101010101010101010101010101010 >> counter;
+    eff_3_en  <= 32'b11101110010001001110111001000100 >> counter;
+    eff_3_a   <= 32'b11111010111110100101000001010000 >> counter;
 end
 
 always @(posedge eff_0_trg)
@@ -71,11 +79,22 @@ always @(posedge eff_2_trgA, posedge eff_2_trgB)
     if (eff_2_en)
         $display("repeated");
 
+always @(posedge eff_3_trg)
+    if (eff_3_en) begin
+        $display("%02d: eff3 vvv", counter);
+`ifdef NO_ASSERT
+        if (!eff_3_a)
+            $display("Failed assertion eff3 at");
+`else
+        eff3: assert(eff_3_a);
+`endif
+    end
+
 `ifdef __ICARUS__
 initial gclk = 0;
 always @(gclk) gclk <= #5 !gclk;
 always @(posedge gclk)
-    if (counter == 31)
+    if (counter == 32)
         $finish(0);
 `endif