diff --git a/tests/include/test/helpers.h b/tests/include/test/helpers.h
index 134e49b..ad6b9d7 100644
--- a/tests/include/test/helpers.h
+++ b/tests/include/test/helpers.h
@@ -77,7 +77,7 @@
  *
  * For convenience, dies if allocation fails.
  */
-unsigned char *unhexify_alloc( const char *ibuf, size_t *olen );
+unsigned char *mbedtls_test_unhexify_alloc( const char *ibuf, size_t *olen );
 
 int hexcmp( uint8_t * a, uint8_t * b, uint32_t a_len, uint32_t b_len );