diff --git a/NEWS b/NEWS
index 5d5c289c5..6c6b3a323 100644
--- a/NEWS
+++ b/NEWS
@@ -3,11 +3,19 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2021-01-24:
+
+- Fixed: an unquoted variable expansion evaluated in a DEBUG trap action caused
+  IFS field splitting to be deactivated in code executed after the trap action.
+  This bug was introduced in ksh 93t+ 2009-11-30.
+
 2021-01-23:
 
 - Fixed: when the DEBUG trap was redefined in a subshell, the DEBUG trap in
   the parent environment was corrupted or the shell crashed.
   When a redirection was used in a DEBUG trap action, the trap was disabled.
+  DEBUG traps were also incorrectly inherited by subshells and ksh functions.
+  All this was caused by a bug introduced in ksh 93t 2008-07-25.
 
 2021-01-22:
 
@@ -18,6 +26,7 @@ Any uppercase BUG_* names are modernish shell bug IDs.
 
 - Fixed: executing a DEBUG trap in a command substitution had side effects
   on the exit status ($?) of non-trap commands.
+  This bug was introduced in ksh 93t 2008-11-04.
 
 - The typeset builtin command now gives an informative error message if an
   incompatible combination of options is given.
diff --git a/src/cmd/ksh93/COMPATIBILITY b/src/cmd/ksh93/COMPATIBILITY
index 970f78e01..c3d5e0c1f 100644
--- a/src/cmd/ksh93/COMPATIBILITY
+++ b/src/cmd/ksh93/COMPATIBILITY
@@ -80,6 +80,10 @@ For more details, see the NEWS file and for complete details, see the git log.
 12.	The 'typeset' builtin now properly detects and reports options that
 	cannot be used together if they are given as part of the same command.
 
+13.	The DEBUG trap has reverted to pre-93t behavior. It is now once again
+	reset like other traps upon entering a subshell or ksh-style function,
+	as documented, and it is no longer prone to crash or get corrupted.
+
 ____________________________________________________________________________
 
 		KSH-93 VS. KSH-88
diff --git a/src/cmd/ksh93/include/version.h b/src/cmd/ksh93/include/version.h
index 3bd045bc4..98088afc7 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	"2021-01-23"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2021-01-24"	/* 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 ${.sh.version}, so don't change amount of whitespace. */
diff --git a/src/cmd/ksh93/sh/fault.c b/src/cmd/ksh93/sh/fault.c
index 1873b6378..91378ed7e 100644
--- a/src/cmd/ksh93/sh/fault.c
+++ b/src/cmd/ksh93/sh/fault.c
@@ -451,11 +451,9 @@ int sh_trap(const char *trap, int mode)
 	int	was_verbose = sh_isstate(SH_VERBOSE);
 	int	staktop = staktell();
 	char	*savptr = stakfreeze(0);
-	char	ifstable[256];
 	struct	checkpt buff;
 	Fcin_t	savefc;
 	fcsave(&savefc);
-	memcpy(ifstable,shp->ifstable,sizeof(ifstable));
 	sh_offstate(SH_HISTORY);
 	sh_offstate(SH_VERBOSE);
 	shp->intrap++;
@@ -493,7 +491,6 @@ int sh_trap(const char *trap, int mode)
 		shp->exitval=savxit;
 	stakset(savptr,staktop);
 	fcrestore(&savefc);
-	memcpy(shp->ifstable,ifstable,sizeof(ifstable));
 	if(was_history)
 		sh_onstate(SH_HISTORY);
 	if(was_verbose)
diff --git a/src/cmd/ksh93/tests/basic.sh b/src/cmd/ksh93/tests/basic.sh
index db2ac777b..405a02215 100755
--- a/src/cmd/ksh93/tests/basic.sh
+++ b/src/cmd/ksh93/tests/basic.sh
@@ -745,8 +745,9 @@ got=$(eval 'x=`for i in test; do case $i in test) true;; esac; done`' 2>&1) \
 || err_exit "case in a for loop inside a \`comsub\` caused syntax error (got $(printf %q "$got"))"
 
 # ======
+# Various DEBUG trap fixes: https://github.com/ksh93/ksh/issues/155
+
 # Redirecting disabled the DEBUG trap
-# https://github.com/ksh93/ksh/issues/155 (#1)
 exp=$'LINENO: 4\nfoo\nLINENO: 5\nLINENO: 6\nbar\nLINENO: 7\nbaz'
 got=$({ "$SHELL" -c '
 	PATH=/dev/null
@@ -760,7 +761,6 @@ got=$({ "$SHELL" -c '
 	"(got status $e$( ((e>128)) && print -n / && kill -l "$e"), $(printf %q "$got"))"
 
 # The DEBUG trap crashed when re-trapping inside a subshell
-# https://github.com/ksh93/ksh/issues/155 (#2)
 exp=$'trap -- \': main\' EXIT\ntrap -- \': main\' ERR\ntrap -- \': main\' KEYBD\ntrap -- \': main\' DEBUG'
 got=$({ "$SHELL" -c '
 	PATH=/dev/null
@@ -774,8 +774,20 @@ got=$({ "$SHELL" -c '
 ((!(e = $?))) && [[ $got == "$exp" ]] || err_exit 'Pseudosignal trap failed when re-trapping in subshell' \
 	"(got status $e$( ((e>128)) && print -n / && kill -l "$e"), $(printf %q "$got"))"
 
+# Field splitting broke upon evaluating an unquoted expansion in a DEBUG trap
+exp=$'a\nb\nc'
+got=$({ "$SHELL" -c '
+	PATH=/dev/null
+	v=""
+	trap ": \$v" DEBUG
+	A="a b c"
+	set -- $A
+	printf "%s\n" "$@"
+'; } 2>&1)
+((!(e = $?))) && [[ $got == "$exp" ]] || err_exit 'Field splitting broke after executing DEBUG trap' \
+	"(got status $e$( ((e>128)) && print -n / && kill -l "$e"), $(printf %q "$got"))"
+
 # The DEBUG trap had side effects on the exit status
-# https://github.com/ksh93/ksh/issues/155 (#4)
 trap ':' DEBUG
 (exit 123)
 (((e=$?)==123)) || err_exit "DEBUG trap run in subshell affects exit status (expected 123, got $e)"
@@ -785,5 +797,46 @@ r=`exit 123`
 (((e=$?)==123)) || err_exit "DEBUG trap run in \`comsub\` affects exit status (expected 123, got $e)"
 trap - DEBUG
 
+# The DEBUG trap was incorrectly inherited by subshells
+exp=$'Subshell\nDebug 1\nParentshell'
+got=$(
+	trap 'echo Debug ${.sh.subshell}' DEBUG
+	(echo Subshell)
+	echo Parentshell
+)
+trap - DEBUG  # bug compat
+[[ $got == "$exp" ]] || err_exit "DEBUG trap inherited by subshell" \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
+# The DEBUG trap was incorrectly inherited by ksh functions
+exp=$'Debug 0\nFunctionEnv\nDebug 0\nParentEnv'
+got=$(
+	function myfn
+	{
+		echo FunctionEnv
+	}
+	trap 'echo Debug ${.sh.level}' DEBUG
+	myfn
+	echo ParentEnv
+)
+trap - DEBUG  # bug compat
+[[ $got == "$exp" ]] || err_exit "DEBUG trap inherited by ksh function" \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
+# Make sure the DEBUG trap is still inherited by POSIX functions
+exp=$'Debug 0\nDebug 1\nFunction\nDebug 0\nNofunction'
+got=$(
+	myfn()
+	{
+		echo Function
+	}
+	trap 'echo Debug ${.sh.level}' DEBUG
+	myfn
+	echo Nofunction
+)
+trap - DEBUG  # bug compat
+[[ $got == "$exp" ]] || err_exit "DEBUG trap not inherited by POSIX function" \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))