diff --git a/debug.h b/debug.h
new file mode 100644
index 0000000..aa81760
--- /dev/null
+++ b/debug.h
@@ -0,0 +1,33 @@
+/*!
+ * Polyphonic synthesizer for microcontrollers.  Debug helper.
+ * (C) 2016 Stuart Longland
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA  02110-1301  USA
+ */
+#ifndef _DEBUG_H
+#define _DEBUG_H
+
+#ifdef _DEBUG
+#include <stdio.h>
+#define _DPRINTF(s, a...)	printf(__FILE__ ": %d " s, __LINE__, a)
+#else
+#define _DPRINTF(s, a...)
+#endif
+
+#endif
+/*
+ * vim: set sw=8 ts=8 noet si tw=72
+ */