Index: config.h.in
--- config.h.in.orig
+++ config.h.in
@@ -409,7 +409,11 @@
 
 /* Define to 1 if the system supports fast unaligned access to 16-bit, 32-bit,
    and 64-bit integers. */
-#undef TUKLIB_FAST_UNALIGNED_ACCESS
+#include <endian.h>
+#if !defined(__STRICT_ALIGNMENT)
+#define \
+    TUKLIB_FAST_UNALIGNED_ACCESS 1
+#endif
 
 /* Define to 1 if the amount of physical memory can be detected with
    _system_configuration.physmem. */
