diff --git a/tests/Imakefile b/tests/Imakefile
index 1067a7c..7194905 100644
--- a/tests/Imakefile
+++ b/tests/Imakefile
@@ -25,7 +25,9 @@ ScannerTarget(12to11-test)
           OBJS1 = $(COMMONOBJS) simple_test.o
           SRCS2 = $(COMMONSRCS) damage_test.c
           OBJS2 = $(COMMONOBJS) damage_test.o
-       PROGRAMS = simple_test damage_test
+          SRCS3 = $(COMMONSRCS) transform_test.c
+          OBJS3 = $(COMMONSRCS) transform_test.o
+       PROGRAMS = simple_test damage_test transform_test
 
 /* Make all objects depend on HEADER.  */
 $(OBJS1): $(HEADER)
@@ -35,6 +37,7 @@ depend:: $(HEADER) $(SRCS1)
 
 NormalProgramTarget(simple_test,$(OBJS1),NullParameter,$(LOCAL_LIBRARIES),NullParameter)
 NormalProgramTarget(damage_test,$(OBJS2),NullParameter,$(LOCAL_LIBRARIES),NullParameter)
-DependTarget3($(SRCS1),$(SRCS2),NullParameter)
+NormalProgramTarget(transform_test,$(OBJS3),NullParameter,$(LOCAL_LIBRARIES),NullParameter)
+DependTarget3($(SRCS1),$(SRCS2),$(SRCS3))
 
 all:: $(PROGRAMS)
diff --git a/tests/README b/tests/README
index d9d7407..3ba59b7 100644
--- a/tests/README
+++ b/tests/README
@@ -12,5 +12,10 @@ When tests are being run, the tester must be very careful to not
 interfere with the test operation by moving or resizing the test
 window.  A compositing manager should be running along with the test.
 
+These tests are supposed to test the functionality of the protocol
+translator by connecting to a running instance and validating the
+results of various high-level requests.  In modern parlance, they
+would be ``integration tests''.
+
 Most likely, you do not want to run these tests manually, as the
 `run_tests.sh' script does all the setup for you.
diff --git a/tests/damage_test.c b/tests/damage_test.c
index 742c2cc..40f15a9 100644
--- a/tests/damage_test.c
+++ b/tests/damage_test.c
@@ -30,7 +30,7 @@ static const char *test_names[] =
   {
     "map_window",
     "basic_test_card_image",
-    "basic_damage"
+    "basic_damage",
   };
 
 #define LAST_TEST	BASIC_DAMAGE_KIND
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index ea6e770..b5c18d1 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -18,7 +18,7 @@
 # along with 12to11.  If not, see <https://www.gnu.org/licenses/>.
 
 pushd "$(dirname $0)"
-declare -a standard_tests=( simple_test damage_test )
+declare -a standard_tests=( simple_test damage_test transform_test )
 
 make -C . "${standard_tests[@]}"
 
diff --git a/tests/svnignore.txt b/tests/svnignore.txt
index 65d94fe..87e34f0 100644
--- a/tests/svnignore.txt
+++ b/tests/svnignore.txt
@@ -3,5 +3,6 @@
 vgcore*
 simple_test
 damage_test
+transform_test
 Makefile
 Makefile.bak
diff --git a/tests/test_harness.c b/tests/test_harness.c
index fc3319a..ad55f9d 100644
--- a/tests/test_harness.c
+++ b/tests/test_harness.c
@@ -586,7 +586,7 @@ load_image_data (const char *filename, struct image_data_header *header)
 
   bpp = bytes_per_pixel_for_format (header->format);
 
-  if (!bpp || header->stride < header->height * bpp)
+  if (!bpp || header->stride < header->width * bpp)
     goto error_1;
 
   buffer = malloc (header->stride * header->height);
diff --git a/tests/test_harness.h b/tests/test_harness.h
index 0ca48bd..98d201c 100644
--- a/tests/test_harness.h
+++ b/tests/test_harness.h
@@ -91,3 +91,9 @@ extern void test_init (void);
 extern void test_complete (void) __attribute__ ((noreturn));
 
 #define ARRAYELTS(arr) (sizeof (arr) / sizeof (arr)[0])
+
+#if __GNUC__ >= 7
+#define FALLTHROUGH __attribute__ ((fallthrough))
+#else
+#define FALLTHROUGH ((void) 0)
+#endif