diff --git a/NEWS b/NEWS
index 9745404a7..ff7aac20b 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,10 @@ Any uppercase BUG_* names are modernish shell bug IDs.
 
 2022-02-05:
 
+- Fixed: for indexed arrays, given an unset array member a[i] with i > 0,
+  ${a[i]=value} failed to assign the value and ${v[i]?error} failed to throw
+  an error.
+
 - Fixed: the -a/--allexport shell option incorrectly exported some variables
   with names containing a dot to the environment. Note that the '-x' typeset
   attribute may still be set for them, but this will now not have any
diff --git a/src/cmd/ksh93/include/shell.h b/src/cmd/ksh93/include/shell.h
index ca7cf8265..3de9a7209 100644
--- a/src/cmd/ksh93/include/shell.h
+++ b/src/cmd/ksh93/include/shell.h
@@ -354,6 +354,7 @@ struct Shell_s
 	void		*defpathlist;
 	void		*cdpathlist;
 	char		**argaddr;
+	char		cond_expan;	/* set while processing ${var=val}, ${var:=val}, ${var?err}, ${var:?err} */
 	void		*optlist;
 	struct sh_scoped global;
 	struct checkpt	checkbase;
diff --git a/src/cmd/ksh93/sh/array.c b/src/cmd/ksh93/sh/array.c
index a848be72c..4281c1eba 100644
--- a/src/cmd/ksh93/sh/array.c
+++ b/src/cmd/ksh93/sh/array.c
@@ -1247,7 +1247,7 @@ Namval_t *nv_putsub(Namval_t *np,register char *sp,register long mode)
 					nv_arraychild(np,mp,0);
 					nv_setvtree(mp);
 				}
-				else
+				else if(!sh.cond_expan)
 					ap->val[size].cp = Empty;
 				if(!sp && !array_covered(np,ap))
 					ap->header.nelem++;
diff --git a/src/cmd/ksh93/sh/macro.c b/src/cmd/ksh93/sh/macro.c
index 3f04e415b..72e1ad6dc 100644
--- a/src/cmd/ksh93/sh/macro.c
+++ b/src/cmd/ksh93/sh/macro.c
@@ -1304,27 +1304,28 @@ retry1:
 			if(c=='=' || (c==':' && d=='='))
 				flag |= NV_ASSIGN;
 			flag &= ~NV_NOADD;
+			sh.cond_expan = 1;	/* tell nv_putsub() not to change value from null to empty */
+			np = nv_open(id,sh.var_tree,flag|NV_NOFAIL);
+			sh.cond_expan = 0;
 		}
 #if  SHOPT_FILESCAN
-		if(sh.cur_line && *id=='R' && strcmp(id,"REPLY")==0)
+		else if(sh.cur_line && strcmp(id,REPLYNOD->nvname)==0)
 		{
 			sh.argaddr=0;
 			np = REPLYNOD;
 		}
-		else
 #endif  /* SHOPT_FILESCAN */
+		else
 		{
 			if(sh.argaddr)
 				flag &= ~NV_NOADD;
-			/*
-			 * Get a node pointer (np) to the parameter, if any.
-			 */
 			np = nv_open(id,sh.var_tree,flag|NV_NOFAIL);
-			if(!np)
-			{
-				sfprintf(sh.strbuf,"%s%c",id,0);
-				id = sfstruse(sh.strbuf);
-			}
+		}
+		if(!np)
+		{
+			/* id points to stack, which will be overwritten; save it for error message */
+			sfputr(sh.strbuf,id,-1);
+			id = sfstruse(sh.strbuf);
 		}
 		if(isastchar(mode))
 			var = 0;
diff --git a/src/cmd/ksh93/tests/arrays.sh b/src/cmd/ksh93/tests/arrays.sh
index 8b701406c..b29b6d360 100755
--- a/src/cmd/ksh93/tests/arrays.sh
+++ b/src/cmd/ksh93/tests/arrays.sh
@@ -783,5 +783,25 @@ got=$("$SHELL" -c '
 [[ $exp == $got ]] || err_exit 'Unsetting all elements of an array adds a spurious [0] element' \
 	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 
+# ======
+# https://github.com/ksh93/ksh/issues/383
+unset foo
+exp=bar
+got=$(echo "${foo[42]=bar}")
+[[ $got == "$exp" ]] || err_exit '${array[index]=value} does not assign value' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+exp=baz
+got=$(echo "${foo[42]:=baz}")
+[[ $got == "$exp" ]] || err_exit '${array[index]:=value} does not assign value' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+exp=': parameter not set'
+got=$(set +x; redirect 2>&1; : ${foo[42]?})
+[[ $got == *"$exp" ]] || err_exit '${array[index]?error} does not throw error' \
+	"(expected match of *$(printf %q "$exp"), got $(printf %q "$got"))"
+exp=': parameter null'
+got=$(set +x; redirect 2>&1; foo[42]=''; : ${foo[42]:?})
+[[ $got == *"$exp" ]] || err_exit '${array[index]:?error} does not throw error' \
+	"(expected match of *$(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))