diff --git a/configure.ac b/configure.ac
index f9054676..8a68bc77 100644
--- a/configure.ac
+++ b/configure.ac
@@ -74,7 +74,7 @@ AC_ARG_ENABLE(debug,
 	[debug="$enableval"])
 if test "$debug" = "yes"; then
   # Useless POS gnomecanvasmm doesn't build w/ -pedantic
-  CFLAGS="-O1 -g -DDEBUG"
+  CFLAGS="-O0 -g -DDEBUG"
   CXXFLAGS="$CFLAGS"
 else
   CFLAGS="$CFLAGS -DNDEBUG"
diff --git a/src/JackDriver.cpp b/src/JackDriver.cpp
index 5bb084ed..bbbd8fb4 100644
--- a/src/JackDriver.cpp
+++ b/src/JackDriver.cpp
@@ -140,8 +140,10 @@ JackDriver::refresh()
 		// FIXME: leak?  jack docs don't say
 		const char* const type_str = jack_port_type(port);
 		PortType port_type = JACK_AUDIO;
-		if (!strcmp(type_str, "8 bit raw midi"))
+		if (!strcmp(type_str, JACK_DEFAULT_MIDI_TYPE))
 			port_type = JACK_MIDI;
+		else if (strcmp(type_str, JACK_DEFAULT_AUDIO_TYPE))
+			throw "Unknown JACK port type?";
 
 		m->add_patchage_port(jack_port_short_name(port),
 			(jack_port_flags(port) & JackPortIsInput),