--- a/tests/README
+++ b/tests/README
@@ -28,7 +28,8 @@ writing tests:
 
 - diff will show the current time
 
-  use hg diff | sed "s/\(\(---\|+++\).*\)\t.*/\1/" to strip dates
+  use hg diff | sed "s/\(\(---\|+++\) [^ \t]*\)[ \t].*/\1/" to strip
+  dates
 
 - set -x and pipelines don't generate stable output
 

--- a/tests/test-diffdir
+++ b/tests/test-diffdir
@@ -7,6 +7,6 @@ hg ci -m "a" -d "0 0"
 
 echo 123 > b
 hg add b
-hg diff | sed "s/\(\(---\|+++\).*\)\t.*/\1/"
+hg diff | sed "s/\(\(---\|+++\) [^ \t]*\)[ \t].*/\1/"
 
-hg diff -r tip | sed "s/\(\(---\|+++\).*\)\t.*/\1/"
+hg diff -r tip | sed "s/\(\(---\|+++\) [^ \t]*\)[ \t].*/\1/"

--- a/tests/test-up-local-change
+++ b/tests/test-up-local-change
@@ -13,7 +13,7 @@ cd ../r2
 hg up
 echo abc > a
 hg diff > ../d
-sed "s/\(\(---\|+++\).*\)\t.*/\1/" < ../d
+sed "s/\(\(---\|+++\) [^ \t]*\)[ \t].*/\1/" < ../d
 
 cd ../r1
 echo b > b
@@ -29,5 +29,5 @@ hg --debug up -m
 hg parents
 hg -v history
 hg diff > ../d
-sed "s/\(\(---\|+++\).*\)\t.*/\1/" < ../d
+sed "s/\(\(---\|+++\) [^ \t]*\)[ \t].*/\1/" < ../d