diff --git a/src/pl_alloc.h b/src/pl_alloc.h
index 78df08a..29718eb 100644
--- a/src/pl_alloc.h
+++ b/src/pl_alloc.h
@@ -83,6 +83,9 @@ char *pl_strndup0(void *parent, const char *str, size_t size);
 // `priv` at the address of `pub` + sizeof(pub), rounded up to the maximum
 // alignment requirements.
 
+#if defined(_MSC_VER)
+typedef double max_align_t;
+#endif
 #define PL_ALIGN_MEM(size) PL_ALIGN2(size, alignof(max_align_t))
 
 #define PL_PRIV(pub) \