diff --git a/otherlibs/threads/.depend b/otherlibs/threads/.depend
index 803c7d4bd..e5018a01b 100644
--- a/otherlibs/threads/.depend
+++ b/otherlibs/threads/.depend
@@ -16,3 +16,5 @@ thread.cmo: thread.cmi
 thread.cmx: thread.cmi 
 threadIO.cmo: thread.cmi threadIO.cmi 
 threadIO.cmx: thread.cmx threadIO.cmi 
+threadUnix.cmo: thread.cmi threadUnix.cmi 
+threadUnix.cmx: thread.cmx threadUnix.cmi 
diff --git a/otherlibs/threads/Makefile b/otherlibs/threads/Makefile
index c0fad43ec..7d4026eaf 100644
--- a/otherlibs/threads/Makefile
+++ b/otherlibs/threads/Makefile
@@ -6,7 +6,8 @@ CFLAGS=-I../../byterun -O $(BYTECCCOMPOPTS)
 CAMLC=../../boot/cslrun ../../boot/cslc -I ../../boot -I ../unix
 
 C_OBJS=scheduler.o
-CAML_OBJS=thread.cmo threadIO.cmo mutex.cmo condition.cmo event.cmo
+CAML_OBJS=thread.cmo threadIO.cmo threadUnix.cmo \
+  mutex.cmo condition.cmo event.cmo
 
 all: libthreads.a threads.cma
 
diff --git a/otherlibs/threads/scheduler.c b/otherlibs/threads/scheduler.c
index 9269d42bf..ba01f9137 100644
--- a/otherlibs/threads/scheduler.c
+++ b/otherlibs/threads/scheduler.c
@@ -75,7 +75,6 @@ typedef struct thread_struct * thread_t;
 #define RESUMED_IO Val_int(1)
 #define RESUMED_DELAY Val_int(2)
 #define RESUMED_JOIN Val_int(3)
-#define RESUMED_WAIT Val_int(4)
 
 #define NO_FD Val_int(0)
 #define NO_DELAY Val_unit
@@ -215,6 +214,7 @@ static double timeofday()
 
 #define FOREACH_THREAD(x) x = curr_thread; do { x = x->next;
 #define END_FOREACH(x) } while (x != curr_thread)
+static value alloc_process_status();
 
 static value schedule_thread()
 {
@@ -241,15 +241,15 @@ try_again:
   need_wait = 0;
 
   FOREACH_THREAD(th)
-    if (th->status & BLOCKED_READ) {
+    if (th->status & (BLOCKED_READ - 1)) {
       FD_SET(Int_val(th->fd), &readfds);
       need_select = 1;
     }
-    if (th->status & BLOCKED_WRITE) {
+    if (th->status & (BLOCKED_WRITE - 1)) {
       FD_SET(Int_val(th->fd), &writefds);
       need_select = 1;
     }
-    if (th->status & BLOCKED_DELAY) {
+    if (th->status & (BLOCKED_DELAY - 1)) {
       double th_delay = Double_val(th->delay);
       if (now < 0.0) now = timeofday();
       if (th_delay < now) {
@@ -260,19 +260,20 @@ try_again:
         if (th_delay < delay) delay = th_delay;
       }
     }
-    if (th->status & BLOCKED_JOIN) {
+    if (th->status & (BLOCKED_JOIN - 1)) {
       if (((thread_t)(th->joining))->status == KILLED) {
         th->status = RUNNABLE;
         Assign(th->joining, NO_JOINING);
         th->retval = RESUMED_JOIN;
       }
     }
-    if (th->status & BLOCKED_WAIT) {
-      int status;
-      if (waitpid(Int_val(th->waitpid), &status, WNOHANG) > 0) {
+    if (th->status & (BLOCKED_WAIT - 1)) {
+      int status, pid;
+      pid = waitpid(Int_val(th->waitpid), &status, WNOHANG);
+      if (pid > 0) {
         th->status = RUNNABLE;
         th->waitpid = NO_WAITPID;
-        th->retval = RESUMED_WAIT;
+        Assign(th->retval, alloc_process_status(pid, status));
       } else {
         need_wait = 1;
       }
@@ -315,27 +316,23 @@ try_again:
       /* Some descriptors are ready. 
          Mark the corresponding threads runnable. */
       FOREACH_THREAD(th)
-        switch (th->status) {
-          case BLOCKED_READ:
-            if (FD_ISSET(Int_val(th->fd), &readfds)) {
-              /* Wake up only one thread per fd. */
-              FD_CLR(Int_val(th->fd), &readfds);
-              th->status = RUNNABLE;
-              th->fd = NO_FD;
-              th->retval = RESUMED_IO;
-              if (run_thread == NULL) run_thread = th; /* Found one. */
-            }
-            break;
-          case BLOCKED_WRITE:
-            if (FD_ISSET(Int_val(th->fd), &writefds)) {
-              /* Wake up only one thread per fd. */
-              FD_CLR(Int_val(th->fd), &writefds);
-              th->status = RUNNABLE;
-              th->fd = NO_FD;
-              th->retval = RESUMED_IO;
-              if (run_thread == NULL) run_thread = th; /* Found one. */
-            }
-            break;
+        if (th->status & (BLOCKED_READ - 1)
+            && FD_ISSET(Int_val(th->fd), &readfds)) {
+          /* Wake up only one thread per fd. */
+          FD_CLR(Int_val(th->fd), &readfds);
+          th->status = RUNNABLE;
+          th->fd = NO_FD;
+          th->retval = RESUMED_IO;
+          if (run_thread == NULL) run_thread = th; /* Found one. */
+        }
+        if (th->status & (BLOCKED_WRITE - 1)
+            && FD_ISSET(Int_val(th->fd), &writefds)) {
+          /* Wake up only one thread per fd. */
+          FD_CLR(Int_val(th->fd), &writefds);
+          th->status = RUNNABLE;
+          th->fd = NO_FD;
+          th->retval = RESUMED_IO;
+          if (run_thread == NULL) run_thread = th; /* Found one. */
         }
       END_FOREACH(th);
     }
@@ -481,6 +478,7 @@ value thread_wakeup(thread)     /* ML */
   case SUSPENDED:
     th->status = RUNNABLE;
     th->retval = RESUMED_WAKEUP;
+    break;
   case KILLED:
     failwith("Thread.wakeup: killed thread");
   default:
@@ -525,3 +523,38 @@ value thread_kill(thread)       /* ML */
   return retval;
 }
 
+/* Auxiliary function for allocating the result of a waitpid() call */
+
+#ifndef WIFEXITED
+#define WIFEXITED(status) ((status) & 0xFF == 0)
+#define WEXITSTATUS(status) (((status) >> 8) & 0xFF)
+#define WIFSTOPPED(status) ((status) & 0xFF == 0xFF)
+#define WSTOPSIG(status) (((status) >> 8) & 0xFF)
+#define WTERMSIG(status) ((status) & 0x3F)
+#endif
+
+static value alloc_process_status(pid, status)
+     int pid, status;
+{
+  value st, res;
+  Push_roots(r, 1);
+
+  if (WIFEXITED(status)) {
+    st = alloc(1, 0);
+    Field(st, 0) = Val_int(WEXITSTATUS(status));
+  }
+  else if (WIFSTOPPED(status)) {
+    st = alloc(1, 2);
+    Field(st, 0) = Val_int(WSTOPSIG(status));
+  }
+  else {
+    st = alloc(1, 1);
+    Field(st, 0) = Val_int(WTERMSIG(status));
+  }
+  r[0] = st;
+  res = alloc_tuple(2);
+  Field(res, 0) = Val_int(pid);
+  Field(res, 1) = r[0];
+  Pop_roots();
+  return res;
+}
diff --git a/otherlibs/threads/thread.ml b/otherlibs/threads/thread.ml
index c8606130b..eef49bc86 100644
--- a/otherlibs/threads/thread.ml
+++ b/otherlibs/threads/thread.ml
@@ -22,7 +22,7 @@ type resumption_status =
   | Resumed_io
   | Resumed_delay
   | Resumed_join
-  | Resumed_wait
+  | Resumed_wait of int * Unix.process_status
 
 (* It is mucho important that the primitives that reschedule are called 
    through an ML function call, not directly. That's because when such a
@@ -46,7 +46,8 @@ external thread_wait_timed_write
             = "thread_wait_timed_write"
 external thread_join : t -> unit = "thread_join"
 external thread_delay : float -> unit = "thread_delay"
-external thread_wait_pid : int -> unit = "thread_wait_pid"
+external thread_wait_pid : int -> int * Unix.process_status
+            = "thread_wait_pid"
 external thread_wakeup : t -> unit = "thread_wakeup"
 external thread_self : unit -> t = "thread_self"
 external thread_kill : t -> unit = "thread_kill"
diff --git a/otherlibs/threads/thread.mli b/otherlibs/threads/thread.mli
index 6207e41e4..bf2bf32c5 100644
--- a/otherlibs/threads/thread.mli
+++ b/otherlibs/threads/thread.mli
@@ -61,13 +61,14 @@ val wait_timed_write : Unix.file_descr -> float -> bool
            the amount of time given as second argument (in seconds).
            Return [true] if the file descriptor is ready for input/output
            and [false] if the timeout expired. *)
-val wait_pid : int -> unit
+val wait_pid : int -> int * Unix.process_status
         (* [wait_pid p] suspends the execution of the calling thread
            until the Unix process specified by the process identifier [p]
            terminates. A pid [p] of [-1] means wait for any child.
            A pid of [0] means wait for any child in the same process group
            as the current process. Negative pid arguments represent
-           process groups. *)
+           process groups. Returns the pid of the child caught and
+           its termination status, as per [Unix.wait]. *)
 
 (*--*)
 
diff --git a/otherlibs/threads/threadIO.mli b/otherlibs/threads/threadIO.mli
index ba4f71f76..b1ce30104 100644
--- a/otherlibs/threads/threadIO.mli
+++ b/otherlibs/threads/threadIO.mli
@@ -13,9 +13,9 @@
 
 (* Module [ThreadIO]: thread-compatible input-output operations *)
 
-(* This module reimplements some of the input functions from [Pervasives]
+(* This module reimplements some of the functions from [Pervasives]
    and [Lexing] so that they only block the calling thread, not all threads
-   in the program, if data is not immediately available on the input.
+   in the program, if input or output is not immediately possible.
    See the documentation of the [Pervasives] and [Lexing] modules for
    precise descriptions of the functions below. *)