diff --git a/src/Expr.cc b/src/Expr.cc
index 71b94c7aa7..d70e7573a5 100644
--- a/src/Expr.cc
+++ b/src/Expr.cc
@@ -3113,9 +3113,14 @@ Expr* FieldExpr::Simplify(SimplifyType simp_type)
 	return this;
 	}
 
+int FieldExpr::CanDel() const
+	{
+	return td->FindAttr(ATTR_DEFAULT) || td->FindAttr(ATTR_OPTIONAL);
+	}
+
 void FieldExpr::Assign(Frame* f, Val* v, Opcode opcode)
 	{
-	if ( IsError() || ! v )
+	if ( IsError() )
 		return;
 
 	if ( field < 0 )
@@ -3130,6 +3135,11 @@ void FieldExpr::Assign(Frame* f, Val* v, Opcode opcode)
 		}
 	}
 
+void FieldExpr::Delete(Frame* f)
+	{
+	Assign(f, 0, OP_ASSIGN_IDX);
+	}
+
 Val* FieldExpr::Fold(Val* v) const
 	{
 	Val* result = v->AsRecordVal()->Lookup(field);
diff --git a/src/Expr.h b/src/Expr.h
index 3d07f68df1..0f6ee67106 100644
--- a/src/Expr.h
+++ b/src/Expr.h
@@ -688,8 +688,11 @@ public:
 
 	int Field() const	{ return field; }
 
+	int CanDel() const;
+
 	Expr* Simplify(SimplifyType simp_type);
 	void Assign(Frame* f, Val* v, Opcode op = OP_ASSIGN);
+	void Delete(Frame* f);
 
 	Expr* MakeLvalue();
 
diff --git a/testing/btest/Baseline/istate.sync/receiver.vars.log b/testing/btest/Baseline/istate.sync/receiver.vars.log
index 2d7f88c7da..10ea000b52 100644
--- a/testing/btest/Baseline/istate.sync/receiver.vars.log
+++ b/testing/btest/Baseline/istate.sync/receiver.vars.log
@@ -13,22 +13,22 @@ Jodel
 file "test2" of string
 /^?(abbcdefgh)$?/
 {
+6,
 4,
 5,
-3,
-6,
-2
+2,
+3
 }
 {
+[4, JKL] = 104,
 [3, GHI] = 103,
-[2, DEF] = 103,
-[4, JKL] = 104
+[2, DEF] = 103
 }
 {
-[6767] = /^?(QWERTZ)$?/,
 [12346] = /^?(12345)$?/,
-[12345] = /^?(12345)$?/
+[12345] = /^?(12345)$?/,
+[6767] = /^?(QWERTZ)$?/
 }
 6667/tcp
 [2, 20, 3, 4]
-[a=zxzxzx, b=[a=pop, b=43, c=9.999], c=[a=IOIOI, b=201, c=612.2], d=6.6666]
+[a=zxzxzx, b=[a=pop, b=43, c=9.999], c=[a=IOIOI, b=201, c=612.2], d=6.6666, e=<uninitialized>]
diff --git a/testing/btest/Baseline/istate.sync/sender.vars.log b/testing/btest/Baseline/istate.sync/sender.vars.log
index 2d7f88c7da..10ea000b52 100644
--- a/testing/btest/Baseline/istate.sync/sender.vars.log
+++ b/testing/btest/Baseline/istate.sync/sender.vars.log
@@ -13,22 +13,22 @@ Jodel
 file "test2" of string
 /^?(abbcdefgh)$?/
 {
+6,
 4,
 5,
-3,
-6,
-2
+2,
+3
 }
 {
+[4, JKL] = 104,
 [3, GHI] = 103,
-[2, DEF] = 103,
-[4, JKL] = 104
+[2, DEF] = 103
 }
 {
-[6767] = /^?(QWERTZ)$?/,
 [12346] = /^?(12345)$?/,
-[12345] = /^?(12345)$?/
+[12345] = /^?(12345)$?/,
+[6767] = /^?(QWERTZ)$?/
 }
 6667/tcp
 [2, 20, 3, 4]
-[a=zxzxzx, b=[a=pop, b=43, c=9.999], c=[a=IOIOI, b=201, c=612.2], d=6.6666]
+[a=zxzxzx, b=[a=pop, b=43, c=9.999], c=[a=IOIOI, b=201, c=612.2], d=6.6666, e=<uninitialized>]
diff --git a/testing/btest/Baseline/language.delete-field/output b/testing/btest/Baseline/language.delete-field/output
new file mode 100644
index 0000000000..12d04d02d3
--- /dev/null
+++ b/testing/btest/Baseline/language.delete-field/output
@@ -0,0 +1,4 @@
+a: 20
+20
+a: not set
+5
diff --git a/testing/btest/Baseline/language.wrong-delete-field/output b/testing/btest/Baseline/language.wrong-delete-field/output
new file mode 100644
index 0000000000..c51fb6a37e
--- /dev/null
+++ b/testing/btest/Baseline/language.wrong-delete-field/output
@@ -0,0 +1 @@
+/da/home/robin/bro/master/testing/btest/.tmp/language.wrong-delete-field/wrong-delete-field.bro, line 11 (delete x$a): error, illegal delete statement
diff --git a/testing/btest/istate/sync.bro b/testing/btest/istate/sync.bro
index 04f3f69dcf..d537ca10bc 100644
--- a/testing/btest/istate/sync.bro
+++ b/testing/btest/istate/sync.bro
@@ -39,13 +39,14 @@ type type2: record {
     b: type1;
     c: type1;
     d: double;
+    e: double &optional;
     };
 
 global foo17: type2 = [
 	$a = "yuyuyu",
 	$b = [$a="rec1", $b=100, $c=1.24],
 	$c = [$a="rec2", $b=200, $c=2.24],
-   	$d = 7.77				   
+	$d = 7.77, $e=100.0
 	] &persistent &synchronized;
 
 # Print variables.
@@ -127,6 +128,7 @@ function modify()
 	++foo17$c$b;
 	foo17$c$c = 612.2;
 	foo17$d = 6.6666;
+	delete foo17$e;
 	
 	foo2 = 1234567;
 }
diff --git a/testing/btest/language/delete-field.bro b/testing/btest/language/delete-field.bro
new file mode 100644
index 0000000000..0aad10d55f
--- /dev/null
+++ b/testing/btest/language/delete-field.bro
@@ -0,0 +1,21 @@
+
+# @TEST-EXEC: bro %INPUT >output 2>&1
+# @TEST-EXEC: btest-diff output
+
+type X: record {
+     a: count &optional;
+     b: count &default=5;
+};
+
+function p(x: X)
+	{
+	print x?$a ? fmt("a: %d", x$a) : "a: not set";
+	print x$b;
+	}
+
+
+global x: X = [$a=20, $b=20];
+p(x);
+delete x$a;
+delete x$b;
+p(x);
diff --git a/testing/btest/language/wrong-delete-field.bro b/testing/btest/language/wrong-delete-field.bro
new file mode 100644
index 0000000000..deffe379f4
--- /dev/null
+++ b/testing/btest/language/wrong-delete-field.bro
@@ -0,0 +1,11 @@
+
+# @TEST-EXEC-FAIL: bro %INPUT  >output 2>&1
+# @TEST-EXEC: btest-diff output
+
+type X: record {
+     a: count;
+};
+
+global x: X = [$a=20];
+
+delete x$a;