diff --git a/include/bx/string.h b/include/bx/string.h
index 8932df4..f1eeced 100644
--- a/include/bx/string.h
+++ b/include/bx/string.h
@@ -14,6 +14,10 @@
 #include <string.h>
 #include <wchar.h>  // wchar_t
 
+#ifndef va_copy
+#	define va_copy(_a, _b) (_a) = (_b)
+#endif // va_copy
+
 namespace bx
 {
 	///