diff --git a/drd/tests/Makefile.am b/drd/tests/Makefile.am
index d427b3e43..e7f1f3aa0 100644
--- a/drd/tests/Makefile.am
+++ b/drd/tests/Makefile.am
@@ -231,6 +231,7 @@ EXTRA_DIST =                                        \
 	tc03_re_excl.vgtest                         \
 	tc04_free_lock.stderr.exp-x86               \
 	tc04_free_lock.stderr.exp-ppc               \
+	tc04_free_lock.stderr.exp-s390              \
 	tc04_free_lock.vgtest                       \
 	tc05_simple_race.stderr.exp                 \
 	tc05_simple_race.vgtest                     \
@@ -245,6 +246,7 @@ EXTRA_DIST =                                        \
 	tc09_bad_unlock.stderr.exp-x86              \
 	tc09_bad_unlock.stderr.exp-ppc              \
 	tc09_bad_unlock.stderr.exp-glibc2.8         \
+	tc09_bad_unlock.stderr.exp-s390             \
 	tc09_bad_unlock.vgtest                      \
 	tc10_rec_lock.stderr.exp                    \
 	tc10_rec_lock.vgtest                        \
diff --git a/drd/tests/tc04_free_lock.stderr.exp-s390 b/drd/tests/tc04_free_lock.stderr.exp-s390
new file mode 100644
index 000000000..eafb3db17
--- /dev/null
+++ b/drd/tests/tc04_free_lock.stderr.exp-s390
@@ -0,0 +1,28 @@
+
+Destroying locked mutex: mutex 0x........, recursion count 1, owner 1.
+   at 0x........: free (vg_replace_malloc.c:...)
+   by 0x........: main (tc04_free_lock.c:24)
+mutex 0x........ was first observed at:
+   at 0x........: pthread_mutex_init (drd_pthread_intercepts.c:?)
+   by 0x........: main (tc04_free_lock.c:20)
+
+Destroying locked mutex: mutex 0x........, recursion count 1, owner 1.
+   at 0x........: bar (tc04_free_lock.c:40)
+   by 0x........: process_dl_debug (in /lib64/ld-2.3.4.so)
+   by 0x........: ???
+mutex 0x........ was first observed at:
+   at 0x........: pthread_mutex_lock (drd_pthread_intercepts.c:?)
+   by 0x........: bar (tc04_free_lock.c:38)
+   by 0x........: main (tc04_free_lock.c:26)
+
+Destroying locked mutex: mutex 0x........, recursion count 1, owner 1.
+   at 0x........: foo (tc04_free_lock.c:49)
+   by 0x........: process_dl_debug (in /lib64/ld-2.3.4.so)
+   by 0x........: ???
+mutex 0x........ was first observed at:
+   at 0x........: pthread_mutex_init (drd_pthread_intercepts.c:?)
+   by 0x........: foo (tc04_free_lock.c:46)
+   by 0x........: main (tc04_free_lock.c:27)
+
+
+ERROR SUMMARY: 4 errors from 3 contexts (suppressed: 0 from 0)
diff --git a/drd/tests/tc09_bad_unlock.stderr.exp-s390 b/drd/tests/tc09_bad_unlock.stderr.exp-s390
new file mode 100644
index 000000000..dd84c816e
--- /dev/null
+++ b/drd/tests/tc09_bad_unlock.stderr.exp-s390
@@ -0,0 +1,51 @@
+
+Mutex not locked by calling thread: mutex 0x........, recursion count 0, owner 1.
+   at 0x........: pthread_mutex_unlock (drd_pthread_intercepts.c:?)
+   by 0x........: nearly_main (tc09_bad_unlock.c:27)
+   by 0x........: main (tc09_bad_unlock.c:49)
+mutex 0x........ was first observed at:
+   at 0x........: pthread_mutex_init (drd_pthread_intercepts.c:?)
+   by 0x........: nearly_main (tc09_bad_unlock.c:23)
+   by 0x........: main (tc09_bad_unlock.c:49)
+
+Thread 2:
+Mutex not locked by calling thread: mutex 0x........, recursion count 1, owner 1.
+   at 0x........: pthread_mutex_unlock (drd_pthread_intercepts.c:?)
+   by 0x........: child_fn (tc09_bad_unlock.c:11)
+   by 0x........: vgDrd_thread_wrapper (drd_pthread_intercepts.c:?)
+mutex 0x........ was first observed at:
+   at 0x........: pthread_mutex_init (drd_pthread_intercepts.c:?)
+   by 0x........: nearly_main (tc09_bad_unlock.c:31)
+   by 0x........: main (tc09_bad_unlock.c:49)
+
+Thread 1:
+The object at address 0x........ is not a mutex.
+   at 0x........: pthread_mutex_unlock (drd_pthread_intercepts.c:?)
+   by 0x........: nearly_main (tc09_bad_unlock.c:41)
+   by 0x........: main (tc09_bad_unlock.c:49)
+
+Destroying locked mutex: mutex 0x........, recursion count 1, owner 1.
+   at 0x........: nearly_main (tc09_bad_unlock.c:45)
+   by 0x........: ???
+mutex 0x........ was first observed at:
+   at 0x........: pthread_mutex_init (drd_pthread_intercepts.c:?)
+   by 0x........: nearly_main (tc09_bad_unlock.c:31)
+   by 0x........: main (tc09_bad_unlock.c:49)
+
+---------------------
+Mutex not locked by calling thread: mutex 0x........, recursion count 0, owner 1.
+   at 0x........: pthread_mutex_unlock (drd_pthread_intercepts.c:?)
+   by 0x........: nearly_main (tc09_bad_unlock.c:27)
+   by 0x........: main (tc09_bad_unlock.c:50)
+mutex 0x........ was first observed at:
+   at 0x........: pthread_mutex_init (drd_pthread_intercepts.c:?)
+   by 0x........: nearly_main (tc09_bad_unlock.c:23)
+   by 0x........: main (tc09_bad_unlock.c:50)
+
+The object at address 0x........ is not a mutex.
+   at 0x........: pthread_mutex_unlock (drd_pthread_intercepts.c:?)
+   by 0x........: nearly_main (tc09_bad_unlock.c:41)
+   by 0x........: main (tc09_bad_unlock.c:50)
+
+
+ERROR SUMMARY: 8 errors from 6 contexts (suppressed: 0 from 0)