diff --git a/testing/scripts/diff-remove-timestamps b/testing/scripts/diff-remove-timestamps
index cbb5aa5c0e..e235746f93 100755
--- a/testing/scripts/diff-remove-timestamps
+++ b/testing/scripts/diff-remove-timestamps
@@ -2,5 +2,13 @@
 #
 # Replace anything which looks like timestamps with XXXs (including the #start/end markers in logs).
 
+# Get us "modern" regexps with sed.
+if [ `uname` == "Linux" ]; then
+   sed="sed"
+else
+   sed="sed -E"
+fi
+
+# The first sed uses a "basic" regexp, the 2nd a "modern:.
 sed 's/[0-9]\{10\}\.[0-9]\{2,8\}/XXXXXXXXXX.XXXXXX/g' | \
-sed 's/^#\(start\|end\).\(19\|20\)..-..-..-..-..-..$/#\1 XXXX-XX-XX-XX-XX-XX/g'
+$sed 's/^#(start|end).(19|20)..-..-..-..-..-..$/#\1 XXXX-XX-XX-XX-XX-XX/g'