diff --git a/check.t b/check.t
index cd9ee40..ccd12d1 100644
--- a/check.t
+++ b/check.t
@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.737 2016/06/26 00:06:43 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.738 2016/06/26 00:09:32 tg Exp $
 # -*- mode: sh -*-
 #-
 # Copyright © 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
@@ -2613,6 +2613,10 @@ stdin:
 	eval "$fnd"
 	foo
 	print -r -- "| va={$va} vb={$vb} vc={$vc} vd={$vd} |"
+	x=y
+	foo
+	typeset -f foo
+	print -r -- "| vc={$vc} vd={$vd} |"
 	# check append
 	v=<<-
 		vapp1
@@ -2638,6 +2642,19 @@ expected-stdout:
 	} vc={=c u \x40=
 	} vd={=d $x \x40=
 	} |
+	function foo {
+		vc=<<- 
+	=c $x \x40=
+	<<
+	
+		vd=<<-"" 
+	=d $x \x40=
+	
+	
+	} 
+	| vc={=c y \x40=
+	} vd={=d $x \x40=
+	} |
 	| vapp1^vapp2^ |
 ---
 name: heredoc-12
diff --git a/exec.c b/exec.c
index 962bc2a..a75f489 100644
--- a/exec.c
+++ b/exec.c
@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/exec.c,v 1.173 2016/04/09 16:41:07 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/exec.c,v 1.174 2016/06/26 00:09:35 tg Exp $");
 
 #ifndef MKSH_DEFAULT_EXECSHELL
 #define MKSH_DEFAULT_EXECSHELL	MKSH_UNIXROOT "/bin/sh"
@@ -60,7 +60,6 @@ execute(struct op * volatile t,
 	const char *s, *ccp;
 	struct ioword **iowp;
 	struct tbl *tp = NULL;
-	char *cp;
 
 	if (t == NULL)
 		return (0);
@@ -79,11 +78,18 @@ execute(struct op * volatile t,
 
 	/* we want to run an executable, do some variance checks */
 	if (t->type == TCOM) {
+		/*
+		 * Clear subst_exstat before argument expansion. Used by
+		 * null commands (see comexec() and c_eval()) and by c_set().
+		 */
+		subst_exstat = 0;
+
+		/* for $LINENO */
+		current_lineno = t->lineno;
+
 		/* check if this is 'var=<<EOF' */
-		/*XXX this is broken, don’t use! */
-		/*XXX https://bugs.launchpad.net/mksh/+bug/1380389 */
 		if (
-		    /* we have zero arguments, i.e. no programme to run */
+		    /* we have zero arguments, i.e. no program to run */
 		    t->args[0] == NULL &&
 		    /* we have exactly one variable assignment */
 		    t->vars[0] != NULL && t->vars[1] == NULL &&
@@ -97,42 +103,20 @@ execute(struct op * volatile t,
 		    /* and has no right-hand side (i.e. "varname=") */
 		    ccp[0] == CHAR && ((ccp[1] == '=' && ccp[2] == EOS) ||
 		    /* or "varname+=" */ (ccp[1] == '+' && ccp[2] == CHAR &&
-		    ccp[3] == '=' && ccp[4] == EOS)) &&
-		    /* plus we can have a here document content */
-		    herein(t->ioact[0], &cp) == 0 && cp && *cp) {
-			char *sp = cp, *dp;
-			size_t n = ccp - t->vars[0] + (ccp[1] == '+' ? 4 : 2);
-			size_t z;
+		    ccp[3] == '=' && ccp[4] == EOS))) {
+			char *cp, *dp;
 
-			/* drop redirection (will be garbage collected) */
-			t->ioact = NULL;
-
-			/* set variable to its expanded value */
-			z = strlen(cp);
-			if (notoktomul(z, 2) || notoktoadd(z * 2, n + 1))
-				internal_errorf(Toomem, (size_t)-1);
-			dp = alloc(z * 2 + n + 1, APERM);
-			memcpy(dp, t->vars[0], n);
-			t->vars[0] = dp;
-			dp += n;
-			while (*sp) {
-				*dp++ = QCHAR;
-				*dp++ = *sp++;
-			}
-			*dp = EOS;
+			if ((rv = herein(t->ioact[0], &cp) /*? 1 : 0*/))
+				cp = NULL;
+			dp = shf_smprintf("%s%s", evalstr(t->vars[0],
+			    DOASNTILDE | DOSCALAR), rv ? null : cp);
+			typeset(dp, Flag(FEXPORT) ? EXPORT : 0, 0, 0, 0);
 			/* free the expanded value */
 			afree(cp, APERM);
+			afree(dp, ATEMP);
+			goto Break;
 		}
 
-		/*
-		 * Clear subst_exstat before argument expansion. Used by
-		 * null commands (see comexec() and c_eval()) and by c_set().
-		 */
-		subst_exstat = 0;
-
-		/* for $LINENO */
-		current_lineno = t->lineno;
-
 		/*
 		 * POSIX says expand command words first, then redirections,
 		 * and assignments last..
diff --git a/tree.c b/tree.c
index 5dc3a76..adf6803 100644
--- a/tree.c
+++ b/tree.c
@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/tree.c,v 1.84 2016/06/26 00:07:31 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/tree.c,v 1.85 2016/06/26 00:09:35 tg Exp $");
 
 #define INDENT	8
 
@@ -49,6 +49,7 @@ ptree(struct op *t, int indent, struct shf *shf)
 	struct ioword **ioact;
 	struct op *t1;
 	int i;
+	const char *ccp;
 
  Chain:
 	if (t == NULL)
@@ -56,12 +57,9 @@ ptree(struct op *t, int indent, struct shf *shf)
 	switch (t->type) {
 	case TCOM:
 		prevent_semicolon = false;
-		/*
-		 * special-case 'var=<<EOF' (rough; see
-		 * exec.c:execute() for full code)
-		 */
+		/* special-case 'var=<<EOF' (cf. exec.c:execute) */
 		if (
-		    /* we have zero arguments, i.e. no programme to run */
+		    /* we have zero arguments, i.e. no program to run */
 		    t->args[0] == NULL &&
 		    /* we have exactly one variable assignment */
 		    t->vars[0] != NULL && t->vars[1] == NULL &&
@@ -69,7 +67,13 @@ ptree(struct op *t, int indent, struct shf *shf)
 		    t->ioact != NULL && t->ioact[0] != NULL &&
 		    t->ioact[1] == NULL &&
 		    /* of type "here document" (or "here string") */
-		    (t->ioact[0]->ioflag & IOTYPE) == IOHERE) {
+		    (t->ioact[0]->ioflag & IOTYPE) == IOHERE &&
+		    /* the variable assignment begins with a valid varname */
+		    (ccp = skip_wdvarname(t->vars[0], true)) != t->vars[0] &&
+		    /* and has no right-hand side (i.e. "varname=") */
+		    ccp[0] == CHAR && ((ccp[1] == '=' && ccp[2] == EOS) ||
+		    /* or "varname+=" */ (ccp[1] == '+' && ccp[2] == CHAR &&
+		    ccp[3] == '=' && ccp[4] == EOS))) {
 			fptreef(shf, indent, "%S", t->vars[0]);
 			break;
 		}