diff --git a/NEWS b/NEWS
index 14e58d54a..a97a53f0e 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,11 @@ For full details, see the git log at:
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2020-06-09:
+
+- The 'unalias' builtin will now return a non-zero status if it tries
+  to remove a previously set alias that is not currently set.
+
 2020-06-08:
 
  - Fix an issue with the up arrow key in Emacs editing mode.
diff --git a/src/cmd/ksh93/bltins/typeset.c b/src/cmd/ksh93/bltins/typeset.c
index 99e7b0517..9b9c2fcbe 100644
--- a/src/cmd/ksh93/bltins/typeset.c
+++ b/src/cmd/ksh93/bltins/typeset.c
@@ -1161,11 +1161,13 @@ static int unall(int argc, char **argv, register Dt_t *troot, Shell_t* shp)
 	register const char *name;
 	volatile int r;
 	Dt_t	*dp;
-	int nflag=0,all=0,isfun,jmpval;
+	int nflag=0,all=0,isalias=0,isfun,jmpval;
 	struct checkpt buff;
 	NOT_USED(argc);
-	if(troot==shp->alias_tree)
+	if(troot==shp->alias_tree) {
+		isalias = 1;
 		name = sh_optunalias;
+	}
 	else
 		name = sh_optunset;
 	while(r = optget(argv,name)) switch(r)
@@ -1281,6 +1283,7 @@ static int unall(int argc, char **argv, register Dt_t *troot, Shell_t* shp)
 				if(shp->subshell)
 					np=sh_assignok(np,0);
 			}
+
 			if(!nv_isnull(np) || nv_size(np) || nv_isattr(np,~(NV_MINIMAL|NV_NOFREE)))
 				_nv_unset(np,0);
 			if(troot==shp->var_tree && shp->st.real_fun && (dp=shp->var_tree->walk) && dp==shp->st.real_fun->sdict)
@@ -1298,6 +1301,13 @@ static int unall(int argc, char **argv, register Dt_t *troot, Shell_t* shp)
 				while((troottmp = troottmp->view) && (np = nv_search(name,troottmp,0)) && is_afunction(np))
 					nv_delete(np,troottmp,0);
 			}
+			/* The alias has been unset by call to _nv_unset, remove it from the tree */
+			else if(isalias) {
+				if(nv_isattr(np, NV_NOFREE))
+					nv_delete(np,troot,NV_NOFREE); /* The alias is in read-only memory (shtab_aliases) */
+				else
+					nv_delete(np,troot,0);
+			}
 #if 0
 			/* causes unsetting local variable to expose global */
 			else if(shp->var_tree==troot && shp->var_tree!=shp->var_base && nv_search((char*)np,shp->var_tree,HASH_BUCKET|HASH_NOSCOPE))
diff --git a/src/cmd/ksh93/tests/alias.sh b/src/cmd/ksh93/tests/alias.sh
index 79dbe4ef2..642034eb9 100755
--- a/src/cmd/ksh93/tests/alias.sh
+++ b/src/cmd/ksh93/tests/alias.sh
@@ -103,6 +103,16 @@ fi
 ( alias :pr=print) 2> /dev/null || err_exit 'alias beginning with : fails'
 ( alias p:r=print) 2> /dev/null || err_exit 'alias with : in name fails'
 
-unalias no_such_alias &&  err_exit 'unalias should return non-zero for unknown alias'
+unalias no_such_alias && err_exit 'unalias should return non-zero for unknown alias'
 
+# ======
+# Attempting to unalias a previously set alias twice should be an error
+alias foo=bar
+unalias foo
+unalias foo && err_exit 'unalias should return non-zero when a previously set alias is unaliased twice'
+
+# Removing a predefined alias should work without an error from free(3)
+$SHELL -c 'unalias history' 2> /dev/null || err_exit 'removing a predefined alias does not work'
+
+# ======
 exit $((Errors<125?Errors:125))