diff --git a/t/.gitignore b/t/.gitignore
index 60f6081..39e2520 100644
--- a/t/.gitignore
+++ b/t/.gitignore
@@ -19,3 +19,4 @@ test2.args
 /shellfile
 /nonshelltest
 /*.vartest
+/atime2
diff --git a/t/atime.do b/t/atime.do
new file mode 100644
index 0000000..3543ae1
--- /dev/null
+++ b/t/atime.do
@@ -0,0 +1 @@
+redo atime2
diff --git a/t/atime2.do b/t/atime2.do
new file mode 100644
index 0000000..d4f4fcf
--- /dev/null
+++ b/t/atime2.do
@@ -0,0 +1,6 @@
+# make sure redo doesn't think merely *reading* the old file counts as
+# modifying it in-place.
+cat $1 >/dev/null 2>/dev/null || true
+./tick
+cat $1 >/dev/null 2>/dev/null || true
+echo hello
diff --git a/t/clean.do b/t/clean.do
index cbb166b..24f420c 100644
--- a/t/clean.do
+++ b/t/clean.do
@@ -2,5 +2,6 @@ redo example/clean curse/clean deps/clean "space dir/clean" stamp/clean \
 	defaults-flat/clean defaults-nested/clean
 rm -f broken nonshelltest shellfile mode1 makedir.log chdir1 deltest2 \
 	hello [by]ellow *.o *~ .*~ *.log CC LD passfail silence silence.do \
-	touch1 touch1.do always1 ifcreate[12].dep ifcreate[12] *.vartest
+	touch1 touch1.do always1 ifcreate[12].dep ifcreate[12] *.vartest \
+	atime2
 rm -rf makedir
diff --git a/t/test.do b/t/test.do
index 3378d94..c7b258f 100644
--- a/t/test.do
+++ b/t/test.do
@@ -4,4 +4,4 @@ redo nonshelltest shelltest \
 	deltest deltest2 test.args test2.args passfailtest chdirtest \
 	curse/test deps/test "space dir/test" modetest makedir2 \
 	silencetest touchtest stamp/test alwaystest ifcreate-test \
-	unicode blank/blank vartest
+	unicode blank/blank vartest atime
diff --git a/t/tick b/t/tick
new file mode 100755
index 0000000..f40e325
--- /dev/null
+++ b/t/tick
@@ -0,0 +1,6 @@
+#!/usr/bin/env python
+import time
+
+t1 = int(time.time())
+while int(time.time()) == t1:
+    pass