Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -788,13 +788,10 @@
 	[AC_DEFINE(OF_HAVE_INTTYPES_H, 1, [Whether we have inttypes.h])])
 
 AC_CHECK_HEADER(sys/types.h,
 	[AC_DEFINE(OF_HAVE_SYS_TYPES_H, 1, [Whether we have sys/types.h])])
 
-AC_CHECK_TYPE(max_align_t,
-	[AC_DEFINE(OF_HAVE_MAX_ALIGN_T, 1, [Whether we have max_align_t])])
-
 AC_CHECK_HEADER(stdnoreturn.h,
 	[AC_DEFINE(OF_HAVE_STDNORETURN_H, 1, [Whether we have stdnoreturn.h])])
 
 AC_CHECK_TYPE(wchar_t)
 AC_CHECK_HEADER(wchar.h)

Index: src/macros.h
==================================================================
--- src/macros.h
+++ src/macros.h
@@ -112,19 +112,23 @@
 #else
 # define OF_ALIGNOF(type) __alignof__(type)
 # define OF_ALIGNAS(type) OF_ALIGN(OF_ALIGNOF(type))
 #endif
 
-#if __STDC_VERSION__ >= 201112L && defined(OF_HAVE_MAX_ALIGN_T)
-# define OF_BIGGEST_ALIGNMENT _Alignof(max_align_t)
+#ifdef __BIGGEST_ALIGNMENT__
+# define OF_BIGGEST_ALIGNMENT __BIGGEST_ALIGNMENT__
 #else
-# ifdef __BIGGEST_ALIGNMENT__
-#  define OF_BIGGEST_ALIGNMENT __BIGGEST_ALIGNMENT__
-# else
-#  /* Hopefully no arch needs more than 16 byte alignment */
-#  define OF_BIGGEST_ALIGNMENT 16
-# endif
+/* Hopefully no arch needs more than 16 byte alignment */
+# define OF_BIGGEST_ALIGNMENT 16
+#endif
+/*
+ * We use SSE inline assembly on AMD64 and x86, so it must never be smaller
+ * than 16.
+ */
+#if (defined(OF_AMD64) || defined(OF_X86)) && OF_BIGGEST_ALIGNMENT < 16
+# undef OF_BIGGEST_ALIGNMENT
+# define OF_BIGGEST_ALIGNMENT 16
 #endif
 
 #define OF_PREPROCESSOR_CONCAT2(a, b) a##b
 #define OF_PREPROCESSOR_CONCAT(a, b) OF_PREPROCESSOR_CONCAT2(a, b)
 

Index: src/objfw-defs.h.in
==================================================================
--- src/objfw-defs.h.in
+++ src/objfw-defs.h.in
@@ -15,11 +15,10 @@
 #undef OF_HAVE_FORWARDING_TARGET_FOR_SELECTOR
 #undef OF_HAVE_IPV6
 #undef OF_HAVE_IPX
 #undef OF_HAVE_LIMITS_H
 #undef OF_HAVE_LINK
-#undef OF_HAVE_MAX_ALIGN_T
 #undef OF_HAVE_NETATALK_AT_H
 #undef OF_HAVE_NETAT_APPLETALK_H
 #undef OF_HAVE_NETINET_IN_H
 #undef OF_HAVE_NETINET_TCP_H
 #undef OF_HAVE_NETIPX_IPX_H