diff --git a/src/hostapi/jack/pa_jack.c b/src/hostapi/jack/pa_jack.c
index a800f8e..5ec55c6 100644
--- a/src/hostapi/jack/pa_jack.c
+++ b/src/hostapi/jack/pa_jack.c
@@ -71,6 +71,8 @@
 #include "pa_ringbuffer.h"
 #include "pa_debugprint.h"
 
+#include "pa_jack.h"
+
 static pthread_t mainThread_;
 static char *jackErr_ = NULL;
 static const char* clientName_ = "PortAudio";
diff --git a/src/os/unix/pa_unix_util.c b/src/os/unix/pa_unix_util.c
index 17664ea..5472336 100644
--- a/src/os/unix/pa_unix_util.c
+++ b/src/os/unix/pa_unix_util.c
@@ -236,7 +236,7 @@ pthread_t paUnixMainThread = 0;
 pthread_t paUnixMainThread = 0;
 #endif
 
-PaError PaUnixThreading_Initialize()
+PaError PaUnixThreading_Initialize( void )
 {
     paUnixMainThread = pthread_self();
     return paNoError;
diff --git a/src/os/unix/pa_unix_util.h b/src/os/unix/pa_unix_util.h
index d73c99c..c401f19 100644
--- a/src/os/unix/pa_unix_util.h
+++ b/src/os/unix/pa_unix_util.h
@@ -157,7 +157,7 @@ typedef struct
 
 /** Initialize global threading state.
  */
-PaError PaUnixThreading_Initialize();
+PaError PaUnixThreading_Initialize( void );
 
 /** Perish, passing on eventual error code.
  *