diff --git a/t/.gitignore b/t/.gitignore
index bf9e4ed..1ac69ff 100644
--- a/t/.gitignore
+++ b/t/.gitignore
@@ -1,2 +1,3 @@
 /broken
 /shellfile
+/stress.log
diff --git a/t/950-curse/all.do b/t/950-curse/all.do
index b436dd5..4dd1548 100644
--- a/t/950-curse/all.do
+++ b/t/950-curse/all.do
@@ -1,4 +1,4 @@
-rm -f *.n[012]
+rm -f *.n[012] countall
 
 . ./check-1.sh
 redo-ifchange 1.n0 2.n0 3.n0
diff --git a/t/all.do b/t/all.do
index 4e9f6bb..7aa7c95 100644
--- a/t/all.do
+++ b/t/all.do
@@ -29,3 +29,6 @@ sed 's/\.do$//' | {
         redo "$d"
     done
 }
+
+# if all that worked run a repeated stress test to look for races
+redo stress
diff --git a/t/clean.do b/t/clean.do
index e69f124..a78b666 100644
--- a/t/clean.do
+++ b/t/clean.do
@@ -2,5 +2,5 @@
 sed 's/\.do$//' |
 xargs redo
 
-rm -f broken shellfile *~ .*~
+rm -f broken shellfile *~ .*~ stress.log
 rm -rf 'space home dir'
diff --git a/t/stress.do b/t/stress.do
new file mode 100644
index 0000000..87b5ec3
--- /dev/null
+++ b/t/stress.do
@@ -0,0 +1,10 @@
+rm -f $1.log
+exec >$1.log
+
+# This test twiddles the same files over and over, and seems to trigger race conditions
+# in redo if run repeatedly with a large redo -j.
+for d in $(seq 25); do
+    echo "stress test: cycle $d" >&2
+    ./flush-cache 2>&1
+    redo 950-curse/all 2>&1 || { rv=$?; echo "stress test: log is $1.log" >&2; exit $rv; }
+done