diff --git a/libbuild2-autoconf-tests/checks/byte-order/driver.c b/libbuild2-autoconf-tests/checks/byte-order/driver.c
index 9eea6d5..d8c5c63 100644
--- a/libbuild2-autoconf-tests/checks/byte-order/driver.c
+++ b/libbuild2-autoconf-tests/checks/byte-order/driver.c
@@ -1,11 +1,11 @@
-#include <stdint.h> // uint32_t
-
-#include "config.h"
-
 /* Test that the byte order detected at runtime matches the one detected at
  * compile time.
  */
 
+#include <stdint.h> /* uint32_t */
+
+#include "config.h"
+
 /* Return:
  *
  *   0 if the runtime and compile time byte orders match
diff --git a/libbuild2-autoconf-tests/checks/sizeof/.gitignore b/libbuild2-autoconf-tests/checks/sizeof/.gitignore
new file mode 100644
index 0000000..2b0f929
--- /dev/null
+++ b/libbuild2-autoconf-tests/checks/sizeof/.gitignore
@@ -0,0 +1,2 @@
+config.h
+driver
diff --git a/libbuild2-autoconf-tests/checks/sizeof/buildfile b/libbuild2-autoconf-tests/checks/sizeof/buildfile
new file mode 100644
index 0000000..d03ec6a
--- /dev/null
+++ b/libbuild2-autoconf-tests/checks/sizeof/buildfile
@@ -0,0 +1,11 @@
+exe{driver}: c{driver} h{config}
+
+h{config}: in{config}
+
+c.poptions += "-I$out_base"
+
+if ($c.target.system != 'win32-msvc')
+{
+  c.libs += -pthread
+  c.poptions += -DTEST_PTHREAD
+}
diff --git a/libbuild2-autoconf-tests/checks/sizeof/config.h.in b/libbuild2-autoconf-tests/checks/sizeof/config.h.in
new file mode 100644
index 0000000..64dcc0f
--- /dev/null
+++ b/libbuild2-autoconf-tests/checks/sizeof/config.h.in
@@ -0,0 +1,2 @@
+#undef SIZEOF_OFF_T
+#undef SIZEOF_PTHREAD_T
diff --git a/libbuild2-autoconf-tests/checks/sizeof/driver.c b/libbuild2-autoconf-tests/checks/sizeof/driver.c
new file mode 100644
index 0000000..0ab4017
--- /dev/null
+++ b/libbuild2-autoconf-tests/checks/sizeof/driver.c
@@ -0,0 +1,23 @@
+/* Test more tricky SIZEOF_* checks.
+ */
+
+#include "config.h"
+
+#include <sys/types.h> /* off_t */
+
+#ifdef TEST_PTHREAD
+#  include <pthread.h>
+#endif
+
+#undef NDEBUG
+#include <assert.h>
+
+int
+main ()
+{
+  assert (SIZEOF_OFF_T == sizeof (off_t));
+
+#ifdef TEST_PTHREAD
+  assert (SIZEOF_PTHREAD_T == sizeof (pthread_t));
+#endif
+}