diff --git a/include/bx/string.inl b/include/bx/string.inl
index 825fdd5..42f2a6a 100644
--- a/include/bx/string.inl
+++ b/include/bx/string.inl
@@ -7,6 +7,10 @@
 #	error "Must be included from bx/string.h!"
 #endif // BX_STRING_H_HEADER_GUARD
 
+#if BX_CRT_MSVC && !defined(va_copy)
+#	define va_copy(_a, _b) (_a) = (_b)
+#endif // BX_CRT_MSVC && !defined(va_copy)
+
 namespace bx
 {
 	template <typename Ty>
diff --git a/src/string.cpp b/src/string.cpp
index 8a11080..8bca907 100644
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -15,10 +15,6 @@
 #include <bx/allocator.h>
 #include <bx/hash.h>
 
-#ifndef va_copy
-#	define va_copy(_a, _b) (_a) = (_b)
-#endif // va_copy
-
 namespace bx
 {
 	bool toBool(const char* _str)