diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 31b8f586f3..f0d052013b 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -348,7 +348,7 @@ 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 )