diff --git a/programs/test/ssl_test.c b/programs/test/ssl_test.c
index 6ba4069..f12c2e9 100644
--- a/programs/test/ssl_test.c
+++ b/programs/test/ssl_test.c
@@ -113,7 +113,7 @@
     return( u );
 }
 
-void my_debug( void *ctx, int level, char *str )
+void my_debug( void *ctx, int level, const char *str )
 {
     if( level < ((struct options *) ctx)->debug_level )
         fprintf( stderr, "%s", str );