diff --git a/NEWS b/NEWS
index 6bafbaf61..23b339fbf 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,9 @@ 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.
 
+- The typeset builtin command now gives an informative error message if an
+  incompatible combination of options is given.
+
 2021-01-19:
 
 - Fixed a crash when using 'cd' in a virtual/non-forking subshell in a
diff --git a/src/cmd/ksh93/COMPATIBILITY b/src/cmd/ksh93/COMPATIBILITY
index b5520f409..ed43495a0 100644
--- a/src/cmd/ksh93/COMPATIBILITY
+++ b/src/cmd/ksh93/COMPATIBILITY
@@ -68,8 +68,8 @@ For more details, see the NEWS file and for complete details, see the git log.
 9.	The 'print', 'printf' and 'echo' builtin commands now return a nonzero
 	exit status if an input/output error occurs.
 
-10.	The 'unalias' builtin will now return a non-zero status if it tries to
-	remove a previously set alias that is not currently set.
+10.	The 'typeset' builtin now properly detects and reports options that
+	cannot be used together if they are given as part of the same command.
 
 ____________________________________________________________________________
 
diff --git a/src/cmd/ksh93/bltins/typeset.c b/src/cmd/ksh93/bltins/typeset.c
index e7772caf9..71de5466a 100644
--- a/src/cmd/ksh93/bltins/typeset.c
+++ b/src/cmd/ksh93/bltins/typeset.c
@@ -195,7 +195,7 @@ int    b_typeset(int argc,register char *argv[],Shbltin_t *context)
 	const char	*optstring = sh_opttypeset;
 	Namdecl_t 	*ntp = (Namdecl_t*)context->ptr;
 	Dt_t		*troot;
-	int		isfloat=0, shortint=0, sflag=0;
+	int		isfloat=0, isadjust=0, shortint=0, sflag=0;
 
 	memset((void*)&tdata,0,sizeof(tdata));
 	tdata.sh = context->shp;
@@ -297,6 +297,7 @@ int    b_typeset(int argc,register char *argv[],Shbltin_t *context)
 					tdata.argnum = (int)opt_info.num;
 				if(tdata.argnum < 0)
 					errormsg(SH_DICT,ERROR_exit(1), e_badfield, tdata.argnum);
+				isadjust = 1;
 				if(n=='Z')
 					flag |= NV_ZFILL;
 				else
@@ -377,18 +378,36 @@ endargs:
 		argv--;
 	if((flag&NV_ZFILL) && !(flag&NV_LJUST))
 		flag |= NV_RJUST;
-	if((flag&NV_INTEGER) && (flag&(NV_LJUST|NV_RJUST|NV_ZFILL)))
+	if((isfloat || flag&NV_INTEGER) && isadjust)
+	{
+		errormsg(SH_DICT,2,e_optincompat2,"-i/-F/-E/-X","-L/-R/-Z");
 		error_info.errors++;
+	}
 	if((flag&NV_BINARY) && (flag&(NV_LJUST|NV_UTOL|NV_LTOU)))
+	{
+		errormsg(SH_DICT,2,e_optincompat2,"-b","-L/-u/-l");
 		error_info.errors++;
+	}
 	if((flag&NV_MOVE) && (flag&~(NV_MOVE|NV_VARNAME|NV_ASSIGN)))
+	{
+		errormsg(SH_DICT,2,e_optincompat1,"-m");
 		error_info.errors++;
+	}
 	if((flag&NV_REF) && (flag&~(NV_REF|NV_IDENT|NV_ASSIGN)))
+	{
+		errormsg(SH_DICT,2,e_optincompat1,"-n");
 		error_info.errors++;
+	}
 	if((flag&NV_TYPE) && (flag&~(NV_TYPE|NV_VARNAME|NV_ASSIGN)))
+	{
+		errormsg(SH_DICT,2,e_optincompat1,"-T");
 		error_info.errors++;
+	}
 	if(troot==tdata.sh->fun_tree && ((isfloat || flag&~(NV_FUNCT|NV_TAGGED|NV_EXPORT|NV_LTOU))))
+	{
+		errormsg(SH_DICT,2,e_optincompat1,"-f");
 		error_info.errors++;
+	}
 	if(sflag && troot==tdata.sh->fun_tree)
 	{
 		/* static function */
diff --git a/src/cmd/ksh93/data/builtins.c b/src/cmd/ksh93/data/builtins.c
index f43f506d0..5ad14dff4 100644
--- a/src/cmd/ksh93/data/builtins.c
+++ b/src/cmd/ksh93/data/builtins.c
@@ -1718,7 +1718,7 @@ USAGE_LICENSE
 ;
 
 const char sh_opttypeset[] =
-"+[-1c?\n@(#)$Id: typeset (AT&T Research/ksh93) 2020-07-15 $\n]"
+"+[-1c?\n@(#)$Id: typeset (AT&T Research/ksh93) 2021-01-20 $\n]"
 USAGE_LICENSE
 "[+NAME?typeset - declare or display variables with attributes]"
 "[+DESCRIPTION?Without the \b-f\b option, \btypeset\b sets, unsets, "
@@ -1738,7 +1738,7 @@ USAGE_LICENSE
 "[+?Note also the following builtin command equivalents:]{"
 	"[+autoload?\btypeset -fu\b]"
 	"[+compound?\btypeset -C\b]"
-	"[+float?\btypeset -lE\b]"
+	"[+float ?\btypeset -lE\b]"
 	"[+functions?\btypeset -f\b]"
 	"[+integer?\btypeset -li\b]"
 	"[+nameref?\btypeset -n\b]"
@@ -1768,11 +1768,9 @@ USAGE_LICENSE
 "[l?Without \b-i\b, sets character mapping to \btolower\b. When used "
 	"with \b-i\b, \b-E\b, or \b-F\b indicates long variant.]"
 "[m?Move.  The value is the name of a variable whose value will be "
-	"moved to \aname\a.  The original variable will be unset.  Cannot be "
-	"used with any other options.]"
+	"moved to \aname\a.  The original variable will be unset.]"
 "[n?Name reference.  The value is the name of a variable that \aname\a "
-	"references.  \aname\a cannot contain a \b.\b.  Cannot be used with "
-	"any other options.]"
+	"references.  \aname\a cannot contain a \b.\b.]"
 "[p?Causes the output to be in a format that can be used as input to the "
 	"shell to recreate the attributes for variables.]"
 "[r?Enables readonly.  Once enabled it cannot be disabled.  See "
@@ -1830,6 +1828,9 @@ USAGE_LICENSE
 "\n"
 "\n[name[=value]...]\n"
 " -f [name...]\n"
+" -m [name=name...]\n"
+" -n [name=name...]\n"
+" -T [tname[=(type definition)]...]\n"
 "\n"
 "[+EXIT STATUS?]{"
         "[+0?No errors occurred.]"
diff --git a/src/cmd/ksh93/data/msg.c b/src/cmd/ksh93/data/msg.c
index 0d0e9c5ea..f810421fb 100644
--- a/src/cmd/ksh93/data/msg.c
+++ b/src/cmd/ksh93/data/msg.c
@@ -50,6 +50,8 @@ const char e_query[]		= "no query process";
 const char e_history[]		= "no history file";
 const char e_histopen[]		= "cannot open history file";
 const char e_option[]		= "%s: bad option(s)";
+const char e_optincompat1[]	= "%s cannot be used with other options";
+const char e_optincompat2[]	= "%s cannot be used with %s";
 const char e_toomany[]		= "open file limit exceeded";
 const char e_argtype[]		= "invalid argument of type %c";
 const char e_oneoperand[]	= "one operand expected";
diff --git a/src/cmd/ksh93/include/name.h b/src/cmd/ksh93/include/name.h
index 5f75c717a..f2fef4121 100644
--- a/src/cmd/ksh93/include/name.h
+++ b/src/cmd/ksh93/include/name.h
@@ -230,6 +230,8 @@ extern const Namdisc_t	ENUM_disc;
 extern char		nv_local;
 extern Dtdisc_t		_Nvdisc;
 extern const char	*nv_discnames[];
+extern const char	e_optincompat1[];
+extern const char	e_optincompat2[];
 extern const char	e_subscript[];
 extern const char	e_nullset[];
 extern const char	e_notset[];
diff --git a/src/cmd/ksh93/sh.1 b/src/cmd/ksh93/sh.1
index b8cc46d8f..7a4a5f0f8 100644
--- a/src/cmd/ksh93/sh.1
+++ b/src/cmd/ksh93/sh.1
@@ -7799,13 +7799,30 @@ cannot be exported.
 .PD
 .PP
 The
-.B \-i
-attribute cannot be specified along with
+.BR \-i ,
+.BR \-F ,
+.BR \-E ,
+and
+.B \-X
+options cannot be specified along with
 .BR \-R ,
 .BR \-L ,
-.BR \-Z ,
 or
-.BR \-f .
+.BR \-Z .
+The
+.B \-b
+option cannot be specified along with
+.BR \-L ,
+.BR \-u ,
+or
+.BR \-l .
+The
+.BR \-f ,
+.BR \-m ,
+.BR \-n ,
+and
+.B \-T
+options cannot be used together with any other option.
 .PP
 Using
 .B \+
diff --git a/src/cmd/ksh93/tests/types.sh b/src/cmd/ksh93/tests/types.sh
index 1a7fa16ff..91585325f 100755
--- a/src/cmd/ksh93/tests/types.sh
+++ b/src/cmd/ksh93/tests/types.sh
@@ -639,9 +639,6 @@ bar.foo+=(bam)
 [[ ${bar.foo[0]} == bam ]] || err_exit 'appending to empty array variable in type does not create element 0'
 
 # ======
-# 'typeset -RF' should not create variables that cause crashes
-"$SHELL" -c 'typeset -RF foo=1; test $foo' || err_exit 'typeset -RF does not work'
-
 # Type names that have 'a' as the first letter should be functional
 "$SHELL" -c 'typeset -T al=(typeset bar); al foo=(bar=testset)' || err_exit "type names that start with 'a' don't work"