diff --git a/test/lib/functions.sh b/test/lib/functions.sh
index 0322e5e..5e315d0 100644
--- a/test/lib/functions.sh
+++ b/test/lib/functions.sh
@@ -3,13 +3,12 @@
 SCRIPT_DIR=`dirname "${BASH_SOURCE[0]}"`
 SV2V="$SCRIPT_DIR/../../bin/sv2v +RTS -N1 -RTS"
 
-# USAGE: simulate <vcd-file> <log-file> <top-module> <file> [<file> ...]
+# USAGE: simulate <vcd-file> <log-file> <file> [<file> ...]
 simulate() {
     # arguments
     sim_vcd=$1
     sim_log=$2
-    sim_top=$3
-    shift 3
+    shift 2
     # compile the files
     sim_vcd_tmp=$SHUNIT_TMPDIR/simvcdtmp
     sim_prog=$SHUNIT_TMPDIR/simprog.exe
@@ -19,8 +18,7 @@ simulate() {
         -o $sim_prog \
         -g2005 \
         -gstrict-expr-width \
-        -DTEST_VCD="\"$sim_vcd_tmp\"" \
-        -DTEST_TOP=$sim_top \
+        -DTEST_VCD=\"$sim_vcd_tmp\" \
         "$@" \
         $SCRIPT_DIR/tb_dumper.v \
         2>&1`
@@ -33,10 +31,14 @@ simulate() {
         assertNotNull "iverilog on $1 did not emit any warnings" "$iv_output"
     fi
     # run the simulation
-    $sim_prog > $sim_log
+    $sim_prog -no-date > $sim_log
     assertTrue "simulating $1 failed" $?
-    # remove the date from the VCD
-    sed -e "1,3d" < $sim_vcd_tmp | $SCRIPT_DIR/clean_vcd.py > $sim_vcd
+    # remove parameters from the VCD if present
+    if grep "var parameter" $sim_vcd_tmp > /dev/null; then
+        $SCRIPT_DIR/clean_vcd.py < $sim_vcd_tmp > $sim_vcd
+    elif [ $sim_vcd != "/dev/null" ]; then
+        mv -f $sim_vcd_tmp $sim_vcd
+    fi
 }
 
 assertConverts() {
@@ -167,9 +169,9 @@ simulateAndCompare() {
     cvv_log=$SHUNIT_TMPDIR/cvv.log
 
     # simulate the three files
-    simulate $ref_vcd $ref_log top $ve $tb
-    simulate $cvs_vcd $cvs_log top $cs $tb
-    simulate $cvv_vcd $cvv_log top $cv $tb
+    simulate $ref_vcd $ref_log $ve $tb
+    simulate $cvs_vcd $cvs_log $cs $tb
+    simulate $cvv_vcd $cvv_log $cv $tb
 
     # compare reference verilog to converted succinct
     output=`diff $ref_vcd $cvs_vcd`
diff --git a/test/lib/tb_dumper.v b/test/lib/tb_dumper.v
index 7bd7ec0..b89bb1b 100644
--- a/test/lib/tb_dumper.v
+++ b/test/lib/tb_dumper.v
@@ -1,6 +1,6 @@
 module sv2v_dumper;
     initial begin
         $dumpfile(`TEST_VCD);
-        $dumpvars(1, `TEST_TOP);
+        $dumpvars(1, top);
     end
 endmodule
diff --git a/test/search/run.sh b/test/search/run.sh
index 3ed5144..fc1ab43 100755
--- a/test/search/run.sh
+++ b/test/search/run.sh
@@ -4,7 +4,7 @@ evaluate() {
     design_v=$SHUNIT_TMPDIR/search_design.v
     output_log=$SHUNIT_TMPDIR/search.log
     touch $output_log
-    simulate /dev/null $output_log top <(echo "$1") /dev/null
+    simulate /dev/null $output_log <(echo "$1") /dev/null
     tail -n1 $output_log
 }
 
diff --git a/test/truncate/run.sh b/test/truncate/run.sh
index 362f050..dc26786 100755
--- a/test/truncate/run.sh
+++ b/test/truncate/run.sh
@@ -32,8 +32,8 @@ testNumber() {
 
     # simulate and compare in strict mode
     EXPECT_IVERILOG_WARNINGS=`[ $mode = trunc_ivl_warns ]; echo $?` \
-    simulate /dev/null $ve_log top $ve
-    simulate /dev/null $cs_log top $cs
+    simulate /dev/null $ve_log $ve
+    simulate /dev/null $cs_log $cs
     output=`diff $ve_log $cs_log`
     assertTrue "number literals differ:\n$output" $?
 
@@ -56,8 +56,8 @@ testNumber() {
 
     # simulate and compare in lax mode
     EXPECT_IVERILOG_WARNINGS=`[[ "$number" =~ .\' ]] && [ $mode = trunc_ivl_warns ]; echo $?` \
-    simulate /dev/null $ve_log top -gno-strict-expr-width $ve
-    simulate /dev/null $cs_log top -gno-strict-expr-width $cs
+    simulate /dev/null $ve_log -gno-strict-expr-width $ve
+    simulate /dev/null $cs_log -gno-strict-expr-width $cs
     output=`diff $ve_log $cs_log`
     assertTrue "number literals differ:\n$output" $?
 }