diff --git a/programs/ssl/ssl_client1.c b/programs/ssl/ssl_client1.c
index 455f080..4366853 100644
--- a/programs/ssl/ssl_client1.c
+++ b/programs/ssl/ssl_client1.c
@@ -38,7 +38,7 @@
 
 #define DEBUG_LEVEL 4
 
-void my_debug( void *ctx, int level, char *str )
+void my_debug( void *ctx, int level, const char *str )
 {
     if( level < DEBUG_LEVEL )
     {