diff --git a/t/t0002-gitfile.sh b/t/t0002-gitfile.sh
index c5dbc724b6..4db4ac44c9 100755
--- a/t/t0002-gitfile.sh
+++ b/t/t0002-gitfile.sh
@@ -66,7 +66,7 @@ test_expect_success 'check hash-object' '
 
 test_expect_success 'check cat-file' '
 	git cat-file blob $SHA >actual &&
-	diff -u bar actual
+	test_cmp bar actual
 '
 
 test_expect_success 'check update-index' '
diff --git a/t/t1002-read-tree-m-u-2way.sh b/t/t1002-read-tree-m-u-2way.sh
index e04990eafd..aa9dd580a6 100755
--- a/t/t1002-read-tree-m-u-2way.sh
+++ b/t/t1002-read-tree-m-u-2way.sh
@@ -112,7 +112,7 @@ test_expect_success \
      git update-index --add frotz &&
      git read-tree -m -u $treeH $treeM &&
      git ls-files --stage >6.out &&
-     diff -U0 M.out 6.out &&
+     test_cmp M.out 6.out &&
      check_cache_at frotz clean &&
      sum bozbar frotz nitfol >actual3.sum &&
      cmp M.sum actual3.sum &&
@@ -129,7 +129,7 @@ test_expect_success \
      echo frotz frotz >frotz &&
      git read-tree -m -u $treeH $treeM &&
      git ls-files --stage >7.out &&
-     diff -U0 M.out 7.out &&
+     test_cmp M.out 7.out &&
      check_cache_at frotz dirty &&
      sum bozbar frotz nitfol >actual7.sum &&
      if cmp M.sum actual7.sum; then false; else :; fi &&
@@ -264,7 +264,7 @@ test_expect_success \
      git update-index --add bozbar &&
      git read-tree -m -u $treeH $treeM &&
      git ls-files --stage >18.out &&
-     diff -U0 M.out 18.out &&
+     test_cmp M.out 18.out &&
      check_cache_at bozbar clean &&
      sum bozbar frotz nitfol >actual18.sum &&
      cmp M.sum actual18.sum'
@@ -278,7 +278,7 @@ test_expect_success \
      echo gnusto gnusto >bozbar &&
      git read-tree -m -u $treeH $treeM &&
      git ls-files --stage >19.out &&
-     diff -U0 M.out 19.out &&
+     test_cmp M.out 19.out &&
      check_cache_at bozbar dirty &&
      sum frotz nitfol >actual19.sum &&
      grep -v bozbar  M.sum > expected19.sum &&
@@ -297,7 +297,7 @@ test_expect_success \
      git update-index --add bozbar &&
      git read-tree -m -u $treeH $treeM &&
      git ls-files --stage >20.out &&
-     diff -U0 M.out 20.out &&
+     test_cmp M.out 20.out &&
      check_cache_at bozbar clean &&
      sum bozbar frotz nitfol >actual20.sum &&
      cmp M.sum actual20.sum'
@@ -338,7 +338,7 @@ test_expect_success \
      git update-index --add DF &&
      git read-tree -m -u $treeDF $treeDFDF &&
      git ls-files --stage >DFDFcheck.out &&
-     diff -U0 DFDF.out DFDFcheck.out &&
+     test_cmp DFDF.out DFDFcheck.out &&
      check_cache_at DF/DF clean'
 
 test_done
diff --git a/t/t2201-add-update-typechange.sh b/t/t2201-add-update-typechange.sh
index e15e3eb81b..d24c7d9e5f 100755
--- a/t/t2201-add-update-typechange.sh
+++ b/t/t2201-add-update-typechange.sh
@@ -106,12 +106,12 @@ test_expect_success modify '
 
 test_expect_success diff-files '
 	git diff-files --raw >actual &&
-	diff -u expect-files actual
+	test_cmp expect-files actual
 '
 
 test_expect_success diff-index '
 	git diff-index --raw HEAD -- >actual &&
-	diff -u expect-index actual
+	test_cmp expect-index actual
 '
 
 test_expect_success 'add -u' '
@@ -119,7 +119,7 @@ test_expect_success 'add -u' '
 	cp -p ".git/index" ".git/saved-index" &&
 	git add -u &&
 	git ls-files -s >actual &&
-	diff -u expect-final actual
+	test_cmp expect-final actual
 '
 
 test_expect_success 'commit -a' '
@@ -130,11 +130,11 @@ test_expect_success 'commit -a' '
 	fi &&
 	git commit -m "second" -a &&
 	git ls-files -s >actual &&
-	diff -u expect-final actual &&
+	test_cmp expect-final actual &&
 	rm -f .git/index &&
 	git read-tree HEAD &&
 	git ls-files -s >actual &&
-	diff -u expect-final actual
+	test_cmp expect-final actual
 '
 
 test_done