Workaround unusual SIZE_MAX on SCO OpenServer.
diff --git a/src/common/sysdefs.h b/src/common/sysdefs.h
index 69370ba..5ea6bda 100644
--- a/src/common/sysdefs.h
+++ b/src/common/sysdefs.h
@@ -103,9 +103,12 @@
# define UINT64_MAX UINT64_C(18446744073709551615)
#endif
-// Interix has broken header files, which typedef size_t to unsigned long,
-// but a few lines later define SIZE_MAX to INT32_MAX.
-#ifdef __INTERIX
+// Incorrect(?) SIZE_MAX:
+// - Interix headers typedef size_t to unsigned long,
+// but a few lines later define SIZE_MAX to INT32_MAX.
+// - SCO OpenServer (x86) headers typedef size_t to unsigned int
+// but define SIZE_MAX to INT32_MAX.
+#if defined(__INTERIX) || defined(_SCO_DS)
# undef SIZE_MAX
#endif
