diff --git a/tests/asicworld/run-test.sh b/tests/asicworld/run-test.sh
index 9153f55ff..a204360d7 100755
--- a/tests/asicworld/run-test.sh
+++ b/tests/asicworld/run-test.sh
@@ -1,2 +1,2 @@
 #!/bin/bash
-exec bash ../tools/autotest.sh *.v
+exec bash ../tools/autotest.sh -G *.v
diff --git a/tests/hana/run-test.sh b/tests/hana/run-test.sh
index 199bb916e..89be6d052 100755
--- a/tests/hana/run-test.sh
+++ b/tests/hana/run-test.sh
@@ -1,2 +1,2 @@
 #!/bin/bash
-exec bash ../tools/autotest.sh -l hana_vlib.v test_*.v
+exec bash ../tools/autotest.sh -G -l hana_vlib.v test_*.v
diff --git a/tests/realmath/run-test.sh b/tests/realmath/run-test.sh
index a28863d31..b8e222ad6 100755
--- a/tests/realmath/run-test.sh
+++ b/tests/realmath/run-test.sh
@@ -15,6 +15,7 @@ for ((i = 0; i < 100; i++)); do
 	iverilog -o uut_${idx}_tb uut_${idx}_tb.v uut_${idx}.v uut_${idx}_syn.v
 	./uut_${idx}_tb | tee uut_${idx}.err
 	if test -s uut_${idx}.err; then
+		echo "Note: Make sure that 'iverilog' is an up-to-date git checkout of icarus verilog."
 		exit 1
 	fi
 	rm -f uut_${idx}.err
diff --git a/tests/simple/run-test.sh b/tests/simple/run-test.sh
index 3d00c7eb2..ec1802cbd 100755
--- a/tests/simple/run-test.sh
+++ b/tests/simple/run-test.sh
@@ -6,4 +6,4 @@ if ! which iverilog > /dev/null ; then
   exit 1
 fi
 
-exec bash ../tools/autotest.sh *.v
+exec bash ../tools/autotest.sh -G *.v
diff --git a/tests/tools/autotest.sh b/tests/tools/autotest.sh
index d459f988e..ff431eaf7 100755
--- a/tests/tools/autotest.sh
+++ b/tests/tools/autotest.sh
@@ -11,17 +11,20 @@ backend_opts="-noattr -noexpr"
 scriptfiles=""
 scriptopt=""
 toolsdir="$(cd $(dirname $0); pwd)"
+warn_iverilog_git=false
 
 if [ ! -f $toolsdir/cmp_tbdata -o $toolsdir/cmp_tbdata.c -nt $toolsdir/cmp_tbdata ]; then
 	( set -ex;  gcc -Wall -o $toolsdir/cmp_tbdata $toolsdir/cmp_tbdata.c; ) || exit 1
 fi
 
-while getopts xml:wkvrf:s:p: opt; do
+while getopts xmGl:wkvrf:s:p: opt; do
 	case "$opt" in
 		x)
 			use_xsim=true ;;
 		m)
 			use_modelsim=true ;;
+		G)
+			warn_iverilog_git=true ;;
 		l)
 			libs="$libs $(cd $(dirname $OPTARG); pwd)/$(basename $OPTARG)";;
 		w)
@@ -145,7 +148,13 @@ do
 	elif [ -f ${bn}.skip ]; then
 		mv ${bn}.err ${bn}.skip
 		echo "-> skip"
-	else echo "-> ERROR!"; $keeprunning || exit 1; fi
+	else
+		echo "-> ERROR!"
+		if $warn_iverilog_git; then
+			echo "Note: Make sure that 'iverilog' is an up-to-date git checkout of icarus verilog."
+		fi
+		$keeprunning || exit 1
+	fi
 done
 
 exit 0