diff --git a/php/extension/php-for-tests.sh.in b/php/extension/php-for-tests.sh.in
index 0639ce3ad..283dc47f5 100755
--- a/php/extension/php-for-tests.sh.in
+++ b/php/extension/php-for-tests.sh.in
@@ -1,4 +1,16 @@
 #!/bin/sh
 
 . ./env
+
+# Setting debug or trace isn't very useful because the PHP test script
+# mixes stdout and stderr together and compares this to the expected
+# output, so you'd just get failures for every test.  So there is no
+# good way to debug libguestfs failures in PHP tests, but if an
+# individual test fails locally then you can edit the
+# guestfs_php_*.phpt.in and uncomment the putenv statement, then look
+# at the output.
+
+unset LIBGUESTFS_DEBUG
+unset LIBGUESTFS_TRACE
+
 @PHP@ $@
diff --git a/php/run-php-tests.sh b/php/run-php-tests.sh
index e5cfc0d96..0663b19d9 100755
--- a/php/run-php-tests.sh
+++ b/php/run-php-tests.sh
@@ -24,18 +24,6 @@ cd extension
 # therefore have to load the environment (from php/extension/env which
 # is generated below) at the start of each test script.
 
-# As a consequence of above, LIBGUESTFS_DEBUG=1 and LIBGUESTFS_TRACE=1
-# won't get passed down to the script.  Furthermore, setting debug or
-# trace isn't very useful anyway because the PHP test script mixes
-# stdout and stderr together and compares this to the expected output,
-# so you'd just get failures for every test.  So there is no good way
-# to debug libguestfs failures in PHP tests, but if an individual test
-# fails locally then you can edit the guestfs_php_*.phpt.in and
-# uncomment the putenv statement, then look at the output.
-
-unset LIBGUESTFS_DEBUG
-unset LIBGUESTFS_TRACE
-
 # This makes a file containing the environment variables we want to set.
 rm -f env
 echo "PATH=$PATH" > env