diff --git a/t/preproc-errmsg.sh b/t/preproc-errmsg.sh
index 704562d..891ae43 100644
--- a/t/preproc-errmsg.sh
+++ b/t/preproc-errmsg.sh
@@ -48,7 +48,7 @@ END
 $ACLOCAL
 AUTOMAKE_fails
 
-cat > expected << 'END'
+sort > expected << 'END'
 sub/sub2/more.mk:1: sub_sub2_UNDEFINED must be set with '=' before using '+='
 Makefile.am:2: 'sub/local.mk' included from here
 sub/local.mk:2: 'sub/sub2/more.mk' included from here
@@ -71,7 +71,7 @@ END
 sed -e '/warnings are treated as errors/d' stderr > t1
 sed -e 's/: warning:/:/' t1 > t2
 sed -e 's/: error:/:/' t2 > t3
-sed -e 's/  */ /g' t3 > obtained
+sed -e 's/  */ /g' t3 | sort > obtained
 
 diff expected obtained
 
diff --git a/t/primary-prefix-invalid-couples.tap b/t/primary-prefix-invalid-couples.tap
index 64f11f8..09b332a 100644
-a/t/primary-prefix-invalid-couples.tap
+++ b/t/primary-prefix-invalid-couples.tap
@@ -186,8 +186,10 @@ grep -v 'dir.* not a legitimate directory' stderr && exit 1
 # Check that the same failures are present without the '--add-missing'
 # option.
 mv stderr stderr.old
+cat stderr.old | sort > a
 AUTOMAKE_fails -d "automake error out on mismatched prefix/primary couples"
+cat stderr | sort > b
 command_ok_ "... and with the same diagnostic of 'automake -a'" \
-            diff stderr.old stderr
+            diff a b
 
 :