diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index aa8a0456c..edf1d12b3 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -350,7 +350,7 @@ static int rnd_pseudo_rand( void *rng_state, unsigned char *output, size_t len )
     return( 0 );
 }
 
-static void test_fail( const char *test, int line_no, char* filename )
+static void test_fail( const char *test, int line_no, const char* filename )
 {
     test_errors++;
     if( test_errors == 1 )