diff --git a/Python/thread_cthread.h b/Python/thread_cthread.h
index 79bcc0f..1e731ac 100644
--- a/Python/thread_cthread.h
+++ b/Python/thread_cthread.h
@@ -183,10 +183,11 @@
 	dprintf(("free_sema(%lx) called\n", (long) sema));
 }
 
-void down_sema _P1(sema, type_sema sema)
+int down_sema _P2(sema, type_sema sema, waitflag, int waitflag)
 {
-	dprintf(("down_sema(%lx) called\n", (long) sema));
+	dprintf(("down_sema(%lx, %d) called\n", (long) sema, waitflag));
 	dprintf(("down_sema(%lx) return\n", (long) sema));
+	return -1;
 }
 
 void up_sema _P1(sema, type_sema sema)
diff --git a/Python/thread_foobar.h b/Python/thread_foobar.h
index 772f26b..0bf58f4 100644
--- a/Python/thread_foobar.h
+++ b/Python/thread_foobar.h
@@ -142,10 +142,11 @@
 	dprintf(("free_sema(%lx) called\n", (long) sema));
 }
 
-void down_sema _P1(sema, type_sema sema)
+int down_sema _P2(sema, type_sema sema, waitflag, int waitflag)
 {
-	dprintf(("down_sema(%lx) called\n", (long) sema));
+	dprintf(("down_sema(%lx, %d) called\n", (long) sema, waitflag));
 	dprintf(("down_sema(%lx) return\n", (long) sema));
+	return -1;
 }
 
 void up_sema _P1(sema, type_sema sema)
diff --git a/Python/thread_lwp.h b/Python/thread_lwp.h
index a4e943f..1541334 100644
--- a/Python/thread_lwp.h
+++ b/Python/thread_lwp.h
@@ -190,10 +190,11 @@
 	dprintf(("free_sema(%lx) called\n", (long) sema));
 }
 
-void down_sema _P1(sema, type_sema sema)
+int down_sema _P2(sema, type_sema sema, waitflag, int waitflag)
 {
-	dprintf(("down_sema(%lx) called\n", (long) sema));
+	dprintf(("down_sema(%lx, %d) called\n", (long) sema, waitflag));
 	dprintf(("down_sema(%lx) return\n", (long) sema));
+	return -1;
 }
 
 void up_sema _P1(sema, type_sema sema)
diff --git a/Python/thread_nt.h b/Python/thread_nt.h
index 453e942..18b01be 100644
--- a/Python/thread_nt.h
+++ b/Python/thread_nt.h
@@ -223,7 +223,10 @@
 	CloseHandle((HANDLE) aSemaphore);
 }
 
-void down_sema(type_sema aSemaphore)
+/*
+  XXX must do something about waitflag
+ */
+int down_sema(type_sema aSemaphore, int waitflag)
 {
 	DWORD waitResult;
 
@@ -232,6 +235,7 @@
 	waitResult = WaitForSingleObject( (HANDLE) aSemaphore, INFINITE);
 
 	dprintf(("%ld: down_sema(%lx) return: %l\n", get_thread_ident(),(long) aSemaphore, waitResult));
+	return 0;
 }
 
 void up_sema(type_sema aSemaphore)
diff --git a/Python/thread_os2.h b/Python/thread_os2.h
index f9eda92..00a5244 100644
--- a/Python/thread_os2.h
+++ b/Python/thread_os2.h
@@ -203,9 +203,9 @@
 
 }
 
-void down_sema(type_sema aSemaphore)
+void down_sema(type_sema aSemaphore, int waitflag)
 {
-
+  return -1;
 }
 
 void up_sema(type_sema aSemaphore)
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index 0485e66..a43a2f8 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -274,10 +274,11 @@
 	dprintf(("free_sema(%lx) called\n", (long) sema));
 }
 
-void down_sema _P1(sema, type_sema sema)
+int down_sema _P2(sema, type_sema sema, waitflag, int waitflag)
 {
-	dprintf(("down_sema(%lx) called\n", (long) sema));
+	dprintf(("down_sema(%lx, %d) called\n", (long) sema, waitflag));
 	dprintf(("down_sema(%lx) return\n", (long) sema));
+	return -1;
 }
 
 void up_sema _P1(sema, type_sema sema)
diff --git a/Python/thread_sgi.h b/Python/thread_sgi.h
index 654d4ae..79357a5 100644
--- a/Python/thread_sgi.h
+++ b/Python/thread_sgi.h
@@ -423,12 +423,19 @@
 	usfreesema((usema_t *) sema, shared_arena);
 }
 
-void down_sema _P1(sema, type_sema sema)
+int down_sema _P2(sema, type_sema sema, waitflag, int waitflag)
 {
+	int success;
+
 	dprintf(("down_sema(%lx) called\n", (long) sema));
-	if (uspsema((usema_t *) sema) < 0)
-		perror("uspsema");
+	if (waitflag)
+		success = uspsema((usema_t *) sema);
+	else
+		success = uscpsema((usema_t *) sema);
+	if (success < 0)
+		perror(waitflag ? "uspsema" : "uscpsema");
 	dprintf(("down_sema(%lx) return\n", (long) sema));
+	return success;
 }
 
 void up_sema _P1(sema, type_sema sema)
diff --git a/Python/thread_solaris.h b/Python/thread_solaris.h
index f7fd056..871affa 100644
--- a/Python/thread_solaris.h
+++ b/Python/thread_solaris.h
@@ -25,6 +25,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
+#include <errno.h>
 #include </usr/include/thread.h>
 #undef _POSIX_THREADS
 
@@ -211,12 +212,25 @@
 	free((void *) sema);
 }
 
-void down_sema _P1(sema, type_sema sema)
+int down_sema _P2(sema, type_sema sema, waitflag, int waitflag)
 {
+	int success;
+
 	dprintf(("down_sema(%lx) called\n", (long) sema));
-	if (sema_wait((sema_t *) sema))
-		perror("sema_wait");
-	dprintf(("down_sema(%lx) return\n", (long) sema));
+	if (waitflag)
+		success = sema_wait((sema_t *) sema);
+	else
+		success = sema_trywait((sema_t *) sema);
+	if (success < 0) {
+		if (errno == EBUSY)
+			success = 0;
+		else
+			perror("sema_wait");
+	}
+	else
+		success = !success;
+	dprintf(("down_sema(%lx) return %d\n", (long) sema, success));
+	return success;
 }
 
 void up_sema _P1(sema, type_sema sema)