diff --git a/library/platform_util.c b/library/platform_util.c
index 916a7f4..8fba664 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -143,3 +143,8 @@
 void (*mbedtls_test_hook_test_fail)( const char *, int, const char *);
 #endif /* MBEDTLS_TEST_HOOKS */
 
+/*
+ * Provide an external definition of mbedtls_xor so that the compiler
+ * has the option to not inline it
+ */
+extern inline void mbedtls_xor( unsigned char *r, unsigned char const *a, unsigned char const *b, size_t n );