diff --git a/library/debug.c b/library/debug.c
index 81ee649..3e2466a 100644
--- a/library/debug.c
+++ b/library/debug.c
@@ -78,8 +78,8 @@
     if( ssl->f_dbg == NULL )
         return;
 
-    snprintf( str, maxlen, "%s(%04d): %s() returned %d (0x%x)\n",
-              file, line, text, ret, ret );
+    snprintf( str, maxlen, "%s(%04d): %s() returned %d (-0x%04x)\n",
+              file, line, text, ret, -ret );
 
     str[maxlen] = '\0';
     ssl->f_dbg( ssl->p_dbg, level, str );