diff --git a/libunwind/include/libunwind.h b/libunwind/include/libunwind.h
--- a/libunwind/include/libunwind.h
+++ b/libunwind/include/libunwind.h
@@ -43,6 +43,12 @@
   #define LIBUNWIND_AVAIL
 #endif
 
+#if defined(_WIN32) && defined(__SEH__)
+  #define LIBUNWIND_CURSOR_ALIGNMENT_ATTR __attribute__((__aligned__(16)))
+#else
+  #define LIBUNWIND_CURSOR_ALIGNMENT_ATTR
+#endif
+
 /* error codes */
 enum {
   UNW_ESUCCESS      = 0,     /* no error */
@@ -68,7 +74,7 @@
 
 struct unw_cursor_t {
   uint64_t data[_LIBUNWIND_CURSOR_SIZE];
-};
+} LIBUNWIND_CURSOR_ALIGNMENT_ATTR;
 typedef struct unw_cursor_t unw_cursor_t;
 
 typedef struct unw_addr_space *unw_addr_space_t;
diff --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp
--- a/libunwind/src/UnwindCursor.hpp
+++ b/libunwind/src/UnwindCursor.hpp
@@ -530,6 +530,8 @@
     : _addressSpace(as), _unwindInfoMissing(false) {
   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
                 "UnwindCursor<> does not fit in unw_cursor_t");
+  static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
+                "UnwindCursor<> requires more alignment than unw_cursor_t");
   memset(&_info, 0, sizeof(_info));
   memset(&_histTable, 0, sizeof(_histTable));
   _dispContext.ContextRecord = &_msContext;
@@ -1182,6 +1184,8 @@
       _isSignalFrame(false) {
   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
                 "UnwindCursor<> does not fit in unw_cursor_t");
+  static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
+                "UnwindCursor<> requires more alignment than unw_cursor_t");
   memset(&_info, 0, sizeof(_info));
 }