diff --git a/libs/pbd/pbd/pthread_utils.h b/libs/pbd/pbd/pthread_utils.h
index 64c8ee551e..c6e809157a 100644
--- a/libs/pbd/pbd/pthread_utils.h
+++ b/libs/pbd/pbd/pthread_utils.h
@@ -54,9 +54,15 @@
 /* these are relative to sched_get_priority_max()
  * see pbd_absolute_rt_priority()
  */
-#define PBD_RT_PRI_MAIN -20
-#define PBD_RT_PRI_MIDI -21
-#define PBD_RT_PRI_PROC -22
+#ifdef PLATFORM_WINDOWS
+# define PBD_RT_PRI_MAIN -1
+# define PBD_RT_PRI_MIDI -2
+# define PBD_RT_PRI_PROC -2
+#else
+# define PBD_RT_PRI_MAIN -20
+# define PBD_RT_PRI_MIDI -21
+# define PBD_RT_PRI_PROC -22
+#endif
 
 LIBPBD_API int  pthread_create_and_store (std::string name, pthread_t  *thread, void * (*start_routine)(void *), void * arg);
 LIBPBD_API void pthread_cancel_one (pthread_t thread);
diff --git a/libs/pbd/pthread_utils.cc b/libs/pbd/pthread_utils.cc
index dc948a00e8..78bf942171 100644
--- a/libs/pbd/pthread_utils.cc
+++ b/libs/pbd/pthread_utils.cc
@@ -288,18 +288,19 @@ pbd_absolute_rt_priority (int policy, int priority)
 		/* use default. XXX this should be relative to audio (JACK) thread,
 		 * internal backends use -20 (Audio), -21 (MIDI), -22 (compuation)
 		 */
-		priority = 7; // BaseUI backwards compat.
-	}
-
-	if (priority > 0) {
+		priority = (p_min + p_max) / 2;
+	} else if (priority > 0) {
 		priority += p_min;
 	} else {
-		priority += p_max;
+		priority += p_max + 1;
 	}
-	if (priority > p_max)
+
+	if (priority > p_max) {
 		priority = p_max;
-	if (priority < p_min)
+	}
+	if (priority < p_min) {
 		priority = p_min;
+	}
 	return priority;
 }