new venti library.
diff --git a/src/libventi/debug.c b/src/libventi/debug.c
new file mode 100644
index 0000000..e0452e4
--- /dev/null
+++ b/src/libventi/debug.c
@@ -0,0 +1,17 @@
+#include <u.h>
+#include <libc.h>
+#include <venti.h>
+
+void
+vtdebug(VtConn *z, char *fmt, ...)
+{
+	va_list arg;
+
+	if(z->debug == 0)
+		return;
+
+	va_start(arg, fmt);
+	vfprint(2, fmt, arg);
+	va_end(arg);
+}
+