diff --git a/tests/testlib/wait-on-file b/tests/testlib/wait-on-file
--- a/tests/testlib/wait-on-file
+++ b/tests/testlib/wait-on-file
@@ -11,9 +11,12 @@
 
 timer="$1"
 
-# if the test timeout have been extended, explicitly extend the provided timer
+# Scale the timeout to match the sleep steps below, i.e. 1/0.02.
+timer=$(( 50 * $timer ))
+# If the test timeout have been extended, also scale the timer relative
+# to the normal timing.
 if [ "$HGTEST_TIMEOUT_DEFAULT" -lt "$HGTEST_TIMEOUT" ]; then
-    timer=$(( ( 100 * $timer * $HGTEST_TIMEOUT) / $HGTEST_TIMEOUT_DEFAULT ))
+    timer=$(( ( $timer * $HGTEST_TIMEOUT) / $HGTEST_TIMEOUT_DEFAULT ))
 fi
 
 wait_on="$2"
@@ -28,7 +31,7 @@
 fi
 while [ "$timer" -gt 0 ] && [ ! -f "$wait_on" ]; do
     timer=$(( $timer - 1))
-    sleep 0.01
+    sleep 0.02
 done
 if [ "$timer" -le 0 ]; then
     echo "file not created after $1 seconds: $wait_on" >&2