Add header guards

alsa.h

+#ifndef ALSA_H
+#define ALSA_H
+
 #include <alsa/asoundlib.h>
 
 #include "panelcontrol.h"
@@ -11,3 +14,5 @@ void encoder_callback_add(enum encoder encoder, encoder_callback_fn cb, void *us
 void midi_button_led(snd_seq_t *seq, int port, enum button button, enum button_led_state state);
 
 void alsa(int source, snd_seq_t **seq_ret, int *port_ret);
+
+#endif

pa.h

+#ifndef PA_H
+#define PA_H
+
 extern struct siso_watch_list sink_inputs;
 extern struct siso_watch_list sinks;
 
 void pa();
+
+#endif

pa_siso_watch_list.h

+#ifndef PA_SISO_WATCH_LIST_H
+#define PA_SISO_WATCH_LIST_H
+
 #include <pulse/pulseaudio.h>
 #include <stdbool.h>
 
@@ -29,3 +32,5 @@ uint32_t siso_watch_get_first_or_default(struct siso_watch *w, uint32_t default_
 struct siso_watch *siso_add_name(struct siso_watch_list *wl, const char* name);
 struct siso_watch *siso_get(struct siso_watch_list *wl, const char *name);
 void siso_remove_index(struct siso_watch_list *wl, uint32_t pa_index);
+
+#endif

panelcontrol.h

+#ifndef PANELCONTROL_H
+#define PANELCONTROL_H
+
+
+#include "panelcontrol.h"
 static const char *CLIENT_NAME = "panelcontrol";
 
 enum button {
@@ -44,3 +49,5 @@ enum encoder {
 	ENC7 = 22,
 	ENC8 = 23,
 };
+
+#endif