diff --git a/include/mbedtls/platform_util.h b/include/mbedtls/platform_util.h
index a1ca785..64e6666 100644
--- a/include/mbedtls/platform_util.h
+++ b/include/mbedtls/platform_util.h
@@ -228,7 +228,7 @@
  * \param num   Max-value for the generated random number.
  *
  */ 
-size_t mbedtls_platform_random_in_range( size_t num );
+uint32_t mbedtls_platform_random_in_range( size_t num );
 
 #if defined(MBEDTLS_HAVE_TIME_DATE)
 /**