diff --git a/scripts/data_files/error.fmt b/scripts/data_files/error.fmt
index fdb3ce2..5925904 100644
--- a/scripts/data_files/error.fmt
+++ b/scripts/data_files/error.fmt
@@ -85,7 +85,7 @@
 #if defined(MBEDTLS_TEST_HOOKS)
 static void (*err_add_hook)( int, int, const char *, int );
 
-void mbedtls_set_err_add_hook(void *hook)
+void mbedtls_set_err_add_hook( void (*hook)( int, int, const char *, int ) )
 {
     err_add_hook = hook;
 }