diff --git a/NEWS b/NEWS
index 29ebe9c54..af9e39b3b 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,14 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2021-03-11:
+
+- Fixed an intermittent bug that caused process substitutions to infinitely
+  loop in Linux virtual machines that use systemd.
+
+- Fixed a bug that caused process substitutions to leave lingering processes
+  if the command invoking them never reads from them.
+
 2021-03-09:
 
 - The ${!foo@} and ${!foo*} expansions yield variable names beginning with foo,
diff --git a/src/cmd/ksh93/include/defs.h b/src/cmd/ksh93/include/defs.h
index 41b1729d1..10941a6be 100644
--- a/src/cmd/ksh93/include/defs.h
+++ b/src/cmd/ksh93/include/defs.h
@@ -158,7 +158,7 @@ struct shared
 	Shwait_f	waitevent;
 };
 
-#define _SH_PRIVATE \
+#define __SH_PRIVATE_1 \
 	struct shared	*gd;		/* global data */ \
 	struct sh_scoped st;		/* scoped information */ \
 	Stk_t		*stk;		/* stack pointer */ \
@@ -189,7 +189,6 @@ struct shared
 	char		*comdiv;	/* points to sh -c argument */ \
 	char		*prefix;	/* prefix for compound assignment */ \
 	sigjmp_buf	*jmplist;	/* longjmp return stack */ \
-	char		*fifo;		/* fifo name for process sub */ \
 	pid_t		bckpid;		/* background process id */ \
 	pid_t		cpid; \
 	pid_t		spid; 		/* subshell process id */ \
@@ -282,6 +281,14 @@ struct shared
 	char 		exittrap; \
 	char 		errtrap; \
 	char 		end_fn;
+#if !SHOPT_DEVFD
+#define __SH_PRIVATE_2 \
+	char		*fifo;		/* FIFO name for current process substitution */ \
+	Dt_t		*fifo_tree;	/* for cleaning up process substitution FIFOs */
+#else
+#define	__SH_PRIVATE_2
+#endif
+#define _SH_PRIVATE	__SH_PRIVATE_1 __SH_PRIVATE_2
 
 #include	<shell.h>
 
diff --git a/src/cmd/ksh93/include/version.h b/src/cmd/ksh93/include/version.h
index 175363f3e..c53abee89 100644
--- a/src/cmd/ksh93/include/version.h
+++ b/src/cmd/ksh93/include/version.h
@@ -20,7 +20,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.0.0-alpha"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2021-03-09"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2021-03-11"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2021 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */
diff --git a/src/cmd/ksh93/sh/args.c b/src/cmd/ksh93/sh/args.c
index da193eacf..f9920bc70 100644
--- a/src/cmd/ksh93/sh/args.c
+++ b/src/cmd/ksh93/sh/args.c
@@ -761,6 +761,10 @@ struct argnod *sh_argprocsub(Shell_t *shp,struct argnod *argp)
 	close(pv[1-fd]);
 	sh_iosave(shp,-pv[fd], shp->topfd, (char*)0);
 #else
+	/* remember the FIFO for cleanup in case the command never opens it (see fifo_cleanup(), xec.c) */
+	if(!shp->fifo_tree)
+		shp->fifo_tree = dtopen(&_Nvdisc,Dtoset);
+	nv_search(shp->fifo,shp->fifo_tree,NV_ADD);
 	free(shp->fifo);
 	shp->fifo = 0;
 #endif /* SHOPT_DEVFD */
diff --git a/src/cmd/ksh93/sh/xec.c b/src/cmd/ksh93/sh/xec.c
index c116e3419..850307d82 100644
--- a/src/cmd/ksh93/sh/xec.c
+++ b/src/cmd/ksh93/sh/xec.c
@@ -82,16 +82,34 @@ struct funenv
 /* ========	command execution	========*/
 
 #if !SHOPT_DEVFD
+    static pid_t fifo_save_ppid;
+
     static void fifo_check(void *handle)
     {
 	Shell_t	*shp = (Shell_t*)handle;
-	pid_t pid = getppid();
-	if(pid==1)
+	if(getppid() != fifo_save_ppid)
 	{
 		unlink(shp->fifo);
 		sh_done(shp,0);
 	}
     }
+
+    /* Remove any remaining FIFOs to stop unused process substitutions blocking on trying to open the FIFO */
+    static void fifo_cleanup(void)
+    {
+	if(sh.fifo_tree)
+	{
+		Namval_t	*fifo = dtfirst(sh.fifo_tree);
+		if(fifo)
+		{
+			do
+				unlink(fifo->nvname);
+			while(fifo = dtnext(sh.fifo_tree,fifo));
+			dtclose(sh.fifo_tree);
+			sh.fifo_tree = NIL(Dt_t*);
+		}
+	}
+    }
 #endif /* !SHOPT_DEVFD */
 
 #if _lib_getrusage
@@ -1371,6 +1389,9 @@ int sh_exec(register const Shnode_t *t, int flags)
 						/* failure on special built-ins fatal */
 						if(jmpval<=SH_JMPCMD  && (!nv_isattr(np,BLT_SPC) || command))
 							jmpval=0;
+#if !SHOPT_DEVFD
+						fifo_cleanup();
+#endif
 					}
 					if(bp)
 					{
@@ -1533,6 +1554,9 @@ int sh_exec(register const Shnode_t *t, int flags)
 			else if(!io)
 			{
 			setexit:
+#if !SHOPT_DEVFD
+				fifo_cleanup();
+#endif
 				exitset();
 				break;
 			}
@@ -1591,6 +1615,10 @@ int sh_exec(register const Shnode_t *t, int flags)
 					pipes[2] = 0;
 					coproc_init(shp,pipes);
 				}
+#if !SHOPT_DEVFD
+				if(shp->fifo)
+					fifo_save_ppid = shgd->current_pid;
+#endif
 #if SHOPT_SPAWN
 #   ifdef _lib_fork
 				if(com && !job.jobcontrol)
@@ -1678,6 +1706,14 @@ int sh_exec(register const Shnode_t *t, int flags)
 				struct checkpt *buffp = (struct checkpt*)stkalloc(shp->stk,sizeof(struct checkpt));
 				struct ionod *iop;
 				int	rewrite=0;
+#if !SHOPT_DEVFD
+				if(shp->fifo_tree)
+				{
+					/* do not clean up process substitution FIFOs in child; parent handles this */
+					dtclose(shp->fifo_tree);
+					shp->fifo_tree = NIL(Dt_t*);
+				}
+#endif
 				if(no_fork)
 					sh_sigreset(2);
 				sh_pushcontext(shp,buffp,SH_JMPEXIT);
@@ -1704,16 +1740,24 @@ int sh_exec(register const Shnode_t *t, int flags)
 #if !SHOPT_DEVFD
 				if(shp->fifo && (type&(FPIN|FPOU)))
 				{
-					int	fn,fd = (type&FPIN)?0:1;
-					void	*fifo_timer=sh_timeradd(500,1,fifo_check,(void*)shp);
+					int	fn, fd, save_errno;
+					void	*fifo_timer = sh_timeradd(50,1,fifo_check,(void*)shp);
+					fd = (type&FPIN) ? 0 : 1;
 					fn = sh_open(shp->fifo,fd?O_WRONLY:O_RDONLY);
+					save_errno = errno;
 					timerdel(fifo_timer);
-					sh_iorenumber(shp,fn,fd);
-					sh_close(fn);
-					sh_delay(.001,0);
 					unlink(shp->fifo);
 					free(shp->fifo);
 					shp->fifo = 0;
+					if(fn<0)
+					{
+						if((errno = save_errno) != ENOENT)
+							errormsg(SH_DICT, ERROR_SYSTEM|ERROR_PANIC,
+								 "process substitution: FIFO open failed");
+						sh_done(shp,0);
+					}
+					sh_iorenumber(shp,fn,fd);
+					sh_close(fn);
 					type &= ~(FPIN|FPOU);
 				}
 #endif /* !SHOPT_DEVFD */
@@ -3229,6 +3273,10 @@ static void sh_funct(Shell_t *shp,Namval_t *np,int argn, char *argv[],struct arg
 	char *fname = nv_getval(SH_FUNNAMENOD);
 	struct Level	*lp =(struct Level*)(SH_LEVELNOD->nvfun);
 	int		level, pipepid=shp->pipepid;
+#if !SHOPT_DEVFD
+	Dt_t		*save_fifo_tree = shp->fifo_tree;
+	shp->fifo_tree = NIL(Dt_t*);
+#endif
 	shp->pipepid = 0;
 	sh_stats(STAT_FUNCT);
 	if(!lp->hdr.disc)
@@ -3283,6 +3331,10 @@ static void sh_funct(Shell_t *shp,Namval_t *np,int argn, char *argv[],struct arg
 			_nv_unset(np, NV_RDONLY);
 		}
 	}
+#if !SHOPT_DEVFD
+	fifo_cleanup();
+	shp->fifo_tree = save_fifo_tree;
+#endif
 }
 
 /*
diff --git a/src/cmd/ksh93/tests/io.sh b/src/cmd/ksh93/tests/io.sh
index ace60fe04..67a3ce8e6 100755
--- a/src/cmd/ksh93/tests/io.sh
+++ b/src/cmd/ksh93/tests/io.sh
@@ -715,5 +715,36 @@ got=$(export tmp; "$SHELL" -ec \
 (redirect {v}>$tmp/v.out; echo ok2 >&$v) 2>/dev/null
 [[ -r $tmp/v.out && $(<$tmp/v.out) == ok2 ]] || err_exit 'redirect {varname}>file not working in a subshell'
 
+# ======
+# Test for looping or lingering process substitution processes
+# https://github.com/ksh93/ksh/issues/213
+procsub_pid=$(
+	ulimit -t unlimited 2>/dev/null  # fork the subshell
+	true >(true) <(true) >(true) <(true)
+	echo "$!"
+)
+sleep .1
+if kill -0 "$procsub_pid" 2>/dev/null; then
+	kill -TERM "$procsub_pid" # don't leave around what is effectively a zombie process
+	err_exit "process substitutions loop or linger after parent shell finishes"
+fi
+(true <(true) >(true) <(true) >(true); wait) &
+sleep .1
+if kill -0 $! 2> /dev/null; then
+	kill -TERM $!
+	err_exit "process substitutions linger when unused"
+fi
+
+# process substitutions should work correctly with delays
+procsub_delay()
+{
+	sleep .1  # a delay >50ms, the current fifo_check delay in xec.c
+	cat "$@"
+}
+exp=$'hi\nthere\nworld'
+got=$(procsub_delay <(echo hi) <(echo there) <(echo world))
+[[ $got == "$exp" ]] || err_exit "process substitutions passed to function failed" \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))