diff --git a/library/debug.c b/library/debug.c
index 672e045..2a559b5 100644
--- a/library/debug.c
+++ b/library/debug.c
@@ -65,8 +65,17 @@
 
     va_start( argp, format );
 #if defined(_WIN32)
+#if defined(_TRUNCATE)
     ret = _vsnprintf_s( str, DEBUG_BUF_SIZE, _TRUNCATE, format, argp );
 #else
+    ret = _vsnprintf( str, DEBUG_BUF_SIZE, format, argp );
+    if( ret < 0 || (size_t) ret == DEBUG_BUF_SIZE )
+    {
+        str[DEBUG_BUF_SIZE-1] = '\0';
+        ret = -1;
+    }
+#endif
+#else
     ret = vsnprintf( str, DEBUG_BUF_SIZE, format, argp );
 #endif
     va_end( argp );