diff --git a/defs.h b/defs.h
index 9889efeb..4138894e 100644
--- a/defs.h
+++ b/defs.h
@@ -263,6 +263,7 @@ struct tcb {
 	struct tcb *parent;	/* Parent of this process */
 	int nchildren;		/* # of traced children */
 	int waitpid;		/* pid(s) this process is waiting for */
+	int nzombies;		/* # of formerly traced children now dead */
 #ifdef LINUX
 	int nclone_threads;	/* # of nchildren with CLONE_THREAD */
 	int nclone_detached;	/* # of nchildren with CLONE_DETACHED */
diff --git a/process.c b/process.c
index 71b3ca2b..0a6f8398 100644
--- a/process.c
+++ b/process.c
@@ -1774,7 +1774,17 @@ struct tcb *tcp;
 		/* ??? WTA: fix bug with hanging children */
 
 		if (!(tcp->u_arg[2] & WNOHANG)) {
-			/* There are traced children */
+			/*
+			 * There are traced children.  We'll make the parent
+			 * block to avoid a false ECHILD error due to our
+			 * ptrace having stolen the children.  However,
+			 * we shouldn't block if there are zombies to reap.
+			 * XXX doesn't handle pgrp matches (u_arg[0]==0,<-1)
+			 */
+			if (tcp->nzombies > 0 &&
+			    (tcp->u_arg[0] == -1 ||
+			     pid2tcb(tcp->u_arg[0]) == NULL))
+				return 0;
 			tcp->flags |= TCB_SUSPENDED;
 			tcp->waitpid = tcp->u_arg[0];
 #ifdef TCB_CLONE_THREAD
@@ -1795,6 +1805,14 @@ struct tcb *tcp;
 				"internal_wait: should not have resumed %d\n",
 				tcp->pid);
 	}
+	else if (exiting(tcp) && tcp->u_error == 0 && tcp->u_rval > 0 &&
+		 tcp->nzombies > 0 && pid2tcb(tcp->u_rval) == NULL) {
+		/*
+		 * We just reaped a child we don't know about,
+		 * presumably a zombie we already droptcb'd.
+		 */
+		tcp->nzombies--;
+	}
 	return 0;
 }
 
diff --git a/strace.c b/strace.c
index 8f70d34b..41194b7f 100644
--- a/strace.c
+++ b/strace.c
@@ -621,6 +621,7 @@ int pid;
 			tcp->pid = pid;
 			tcp->parent = NULL;
 			tcp->nchildren = 0;
+			tcp->nzombies = 0;
 #ifdef TCB_CLONE_THREAD
 			tcp->nclone_threads = tcp->nclone_detached = 0;
 			tcp->nclone_waiting = 0;
@@ -1011,6 +1012,10 @@ struct tcb *tcp;
 		if (tcp->flags & TCB_CLONE_THREAD)
 			tcp->parent->nclone_threads--;
 #endif
+#ifdef TCB_CLONE_DETACHED
+		if (!(tcp->flags & TCB_CLONE_DETACHED))
+#endif
+			tcp->parent->nzombies++;
 		tcp->parent = NULL;
 	}