diff --git a/testing/btest/Baseline/language.closure-binding-errors/.stderr b/testing/btest/Baseline/language.closure-binding-errors/.stderr
new file mode 100644
index 0000000000..1b82c68894
--- /dev/null
+++ b/testing/btest/Baseline/language.closure-binding-errors/.stderr
@@ -0,0 +1,10 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+error in <...>/closure-binding-errors.zeek, line 12: a is captured but not used inside lambda (function(){ print no a!})
+error in <...>/closure-binding-errors.zeek, line 13: no such local identifier: a2
+error in <...>/closure-binding-errors.zeek, line 14: b is used inside lambda but not captured (function(){ print b})
+error in <...>/closure-binding-errors.zeek, line 14: a is captured but not used inside lambda (function(){ print b})
+error in <...>/closure-binding-errors.zeek, line 15: a is captured but not used inside lambda (function(){ print b})
+error in <...>/closure-binding-errors.zeek, line 16: b listed multiple times in capture (function(){ print b})
+error in <...>/closure-binding-errors.zeek, line 18: cannot specify global in capture: c
+error in <...>/closure-binding-errors.zeek, line 19: cannot specify type in capture: t
+error in <...>/closure-binding-errors.zeek, line 9 and <...>/closure-binding-errors.zeek, line 20: already defined (a)
diff --git a/testing/btest/Baseline/language.closure-binding-errors/out b/testing/btest/Baseline/language.closure-binding-errors/out
new file mode 100644
index 0000000000..49d861c74c
--- /dev/null
+++ b/testing/btest/Baseline/language.closure-binding-errors/out
@@ -0,0 +1 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
diff --git a/testing/btest/Baseline/language.closure-binding/out b/testing/btest/Baseline/language.closure-binding/out
new file mode 100644
index 0000000000..891492d324
--- /dev/null
+++ b/testing/btest/Baseline/language.closure-binding/out
@@ -0,0 +1,46 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+4, 10
+6, 8
+7, 7
+4, 10
+5, 8
+6, 7
+4, 10
+5, 9
+6, 8
+4, 10
+5, 8
+6, 7
+4, 10
+5, 9
+6, 8
+4
+2, 10, 47
+4
+2, 8, 47
+3
+1, 7, 47
+4
+2, 10, 47
+5
+3, 8, 47
+6
+4, 7, 47
+4
+2, 10, 47
+5
+3, 9, 47
+6
+4, 8, 47
+4
+2, 10, 91
+5
+3, 9, 91
+6
+4, 9, 91
+4
+2, 10, 91
+5
+3, 10, 91
+6
+4, 10, 91
diff --git a/testing/btest/Baseline/language.closure-sending2/recv.recv.out b/testing/btest/Baseline/language.closure-sending2/recv.recv.out
new file mode 100644
index 0000000000..4760591c3c
--- /dev/null
+++ b/testing/btest/Baseline/language.closure-sending2/recv.recv.out
@@ -0,0 +1,27 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+hello :-)
+peer added
+receiver got ping: function 2
+inside: 1 | outside: 11 | global: 100
+77
+receiver got ping: function 1
+begin: 100 | base_step: 2
+begin: 100 | base_step: 2 | step: 76
+178
+receiver got ping: function 2
+inside: 3 | outside: 11 | global: 100
+79
+receiver got ping: function 1
+begin: 100 | base_step: 4
+begin: 100 | base_step: 4 | step: 76
+180
+receiver got ping: function 2
+inside: 5 | outside: 11 | global: 100
+81
+receiver got ping: function 1
+begin: 100 | base_step: 6
+begin: 100 | base_step: 6 | step: 76
+182
+receiver got ping: function 2
+inside: 7 | outside: 11 | global: 100
+83
diff --git a/testing/btest/Baseline/language.closure-sending2/send.send.out b/testing/btest/Baseline/language.closure-sending2/send.send.out
new file mode 100644
index 0000000000..1d644231bc
--- /dev/null
+++ b/testing/btest/Baseline/language.closure-sending2/send.send.out
@@ -0,0 +1,32 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+hello :)
+peer added
+begin: 100 | base_step: 50
+sender got pong: function 2
+inside: 1 | outside: 11 | global: 10
+77
+begin: 100 | base_step: 50
+sender got pong: function 1
+begin: 100 | base_step: 2
+begin: 100 | base_step: 2 | step: 76
+178
+begin: 100 | base_step: 50
+sender got pong: function 2
+inside: 3 | outside: 11 | global: 10
+79
+begin: 100 | base_step: 50
+sender got pong: function 1
+begin: 100 | base_step: 4
+begin: 100 | base_step: 4 | step: 76
+180
+begin: 100 | base_step: 50
+sender got pong: function 2
+inside: 5 | outside: 11 | global: 10
+81
+begin: 100 | base_step: 50
+sender got pong: function 1
+begin: 100 | base_step: 6
+begin: 100 | base_step: 6 | step: 76
+182
+begin: 100 | base_step: 50
+peer lost
diff --git a/testing/btest/language/closure-binding-errors.zeek b/testing/btest/language/closure-binding-errors.zeek
new file mode 100644
index 0000000000..694918dc7d
--- /dev/null
+++ b/testing/btest/language/closure-binding-errors.zeek
@@ -0,0 +1,21 @@
+# @TEST-EXEC-FAIL: zeek -b %INPUT >out
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff .stderr
+
+global c: string;
+type t: addr;
+
+event zeek_init()
+	{
+	local a = 3;
+	local b = "hi there";
+
+	local f1 = function[a]() { print "no a!"; };
+	local f2 = function[a2](a2: addr) { print a2; };
+	local f3 = function[a]() { print b; };
+	local f4 = function[a, b]() { print b; };
+	local f5 = function[b, b]() { print b; };
+	local f6 = function() { print c; };	# should be okay
+	local f7 = function[c]() { print c; };
+	local f8 = function[t]() { local t2: t; };
+	local f9 = function[a]() { local a = 4; };	# error due to shadowing
+	}
diff --git a/testing/btest/language/closure-binding.zeek b/testing/btest/language/closure-binding.zeek
new file mode 100644
index 0000000000..6e1596b6f9
--- /dev/null
+++ b/testing/btest/language/closure-binding.zeek
@@ -0,0 +1,199 @@
+# @TEST-EXEC: zeek -b %INPUT >out
+# @TEST-EXEC: btest-diff out
+
+type mutable_aggregate: record { x: count; };
+
+function reference_capture() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function() { print ++a, --b$x; };
+	f();
+	++a;
+	--b$x;
+	f();
+
+	return f;
+	}
+
+function shallow_copy_capture() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function[a, b]() { print ++a, --b$x; };
+	f();
+	++a;
+	--b$x;
+	f();
+
+	return f;
+	}
+
+function deep_copy_capture() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function[copy a, copy b]() { print ++a, --b$x; };
+	f();
+	++a;
+	--b$x;
+	f();
+
+	return f;
+	}
+
+function mixed_copy_capture_a() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function[copy a, b]() { print ++a, --b$x; };
+	f();
+	++a;
+	--b$x;
+	f();
+
+	return f;
+	}
+
+function mixed_copy_capture_b() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function[a, copy b]() { print ++a, --b$x; };
+	f();
+	++a;
+	--b$x;
+	f();
+
+	return f;
+	}
+
+function reference_capture_double() : function() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function() : function() {
+		local c = mutable_aggregate($x=88);
+		print ++a;
+		local f2 = function() { print a -= 2, --b$x, c$x += 3; };
+		c$x = c$x / 2;
+		return f2;
+		};
+	f()();
+	++a;
+	--b$x;
+	f()();
+
+	return f;
+	}
+
+function shallow_copy_capture_double() : function() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function[a,b]() : function() {
+		local c = mutable_aggregate($x=88);
+		print ++a;
+		local f2 = function[a, b, c]() { print a -= 2, --b$x, c$x += 3; };
+		c$x = c$x / 2;
+		return f2;
+		};
+	f()();
+	++a;
+	--b$x;
+	f()();
+
+	return f;
+	}
+
+function deep_copy1_capture_double() : function() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function[copy a, copy b]() : function() {
+		local c = mutable_aggregate($x=88);
+		print ++a;
+		local f2 = function[a, b, c]() { print a -= 2, --b$x, c$x += 3; };
+		c$x = c$x / 2;
+		return f2;
+		};
+	f()();
+	++a;
+	--b$x;
+	f()();
+
+	return f;
+	}
+
+function deep_copy2_capture_double() : function() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function[a, b]() : function() {
+		local c = mutable_aggregate($x=88);
+		print ++a;
+		local f2 = function[copy a, copy b, copy c]()
+			{ print a -= 2, --b$x, c$x += 3; };
+		c$x = c$x / 2;
+		return f2;
+		};
+	f()();
+	++a;
+	--b$x;
+	f()();
+
+	return f;
+	}
+
+function deep_copy3_capture_double() : function() : function()
+	{
+	local a = 3;
+	local b = mutable_aggregate($x=11);
+	local f = function[copy a, copy b]() : function() {
+		local c = mutable_aggregate($x=88);
+		print ++a;
+		local f2 = function[copy a, copy b, copy c]()
+			{ print a -= 2, --b$x, c$x += 3; };
+		c$x = c$x / 2;
+		return f2;
+		};
+	f()();
+	++a;
+	--b$x;
+	f()();
+
+	return f;
+	}
+
+event zeek_init()
+	{
+	local rc = reference_capture();
+	rc();
+
+	local scc = shallow_copy_capture();
+	scc();
+
+	local dcc = deep_copy_capture();
+	dcc();
+
+	local mcca = mixed_copy_capture_a();
+	mcca();
+
+	local mccb = mixed_copy_capture_b();
+	mccb();
+
+	local rc2 = reference_capture_double();
+	rc2()();
+
+	local scc2 = shallow_copy_capture_double();
+	scc2()();
+
+	local dcc2_1 = deep_copy1_capture_double();
+	dcc2_1()();
+
+	local dcc2_2 = deep_copy2_capture_double();
+	dcc2_2()();
+
+	local dcc2_3 = deep_copy3_capture_double();
+	dcc2_3()();
+	}
diff --git a/testing/btest/language/closure-sending2.zeek b/testing/btest/language/closure-sending2.zeek
new file mode 100644
index 0000000000..c6a421a708
--- /dev/null
+++ b/testing/btest/language/closure-sending2.zeek
@@ -0,0 +1,167 @@
+# @TEST-PORT: BROKER_PORT
+#
+# @TEST-EXEC: btest-bg-run recv "zeek -B broker -b ../recv.zeek >recv.out"
+# @TEST-EXEC: btest-bg-run send "zeek -B broker -b ../send.zeek >send.out"
+#
+# @TEST-EXEC: btest-bg-wait 45
+# @TEST-EXEC: btest-diff recv/recv.out
+# @TEST-EXEC: btest-diff send/send.out
+
+@TEST-START-FILE send.zeek
+
+redef exit_only_after_terminate = T;
+type myfunctype: function(c: count) : function(d: count) : count;
+
+global global_with_same_name = 10;
+
+global ping: event(msg: string, f: myfunctype);
+
+event zeek_init()
+    {
+    print "hello :)";
+    Broker::subscribe("zeek/event/my_topic");
+    Broker::peer("127.0.0.1", to_port(getenv("BROKER_PORT")));
+    }
+
+global n = 0;
+
+function send_event()
+    {
+    # in this frame event_count has an offset of three.
+    # in the receiving frame it has an offset of one.
+    # this tests to ensure that id lookups are being routed properly.
+    local dog = 0;
+    local not_dog = 1;
+    local event_count = 11;
+
+    local log : myfunctype = function[event_count](c: count) : function(d: count) : count
+        {
+        print fmt("inside: %s | outside: %s | global: %s", c, event_count, global_with_same_name);
+        return function[c](d: count) : count { return d + c; };
+        };
+
+	local two_part_adder_maker = function (begin : count) : function (base_step : count) : function ( step : count) : count
+		{
+		return function [begin](base_step : count) : function (step : count) : count
+			{
+                print fmt("begin: %s | base_step: %s", begin, base_step);
+				return function[begin, base_step] (step : count) : count
+					{
+                    print fmt("begin: %s | base_step: %s | step: %s", begin, base_step, step);
+					return (begin += base_step + step); }; }; };
+	
+	local l = two_part_adder_maker(100);
+	local stepper = l(50);
+
+    ++n;
+    ++event_count;
+    if ( n % 2 == 0)
+        {
+        local e2 = Broker::make_event(ping, "function 1", l);
+        Broker::publish("zeek/event/my_topic", e2);
+        }
+    else
+        {
+        local e = Broker::make_event(ping, "function 2", log);
+        Broker::publish("zeek/event/my_topic", e);
+        }
+    }
+
+event Broker::peer_added(endpoint: Broker::EndpointInfo, msg: string)
+    {
+    print "peer added";
+    send_event();
+    }
+
+event Broker::peer_lost(endpoint: Broker::EndpointInfo, msg: string)
+    {
+    print "peer lost";
+    terminate();
+    }
+
+event pong(msg: string, f: myfunctype)
+    {
+    print fmt("sender got pong: %s", msg);
+    local adder = f(n);
+    print adder(76);
+    send_event();
+    }
+
+@TEST-END-FILE
+
+@TEST-START-FILE recv.zeek
+
+redef exit_only_after_terminate = T;
+const events_to_recv = 7;
+type myfunctype: function(c: count) : function(d: count) : count;
+# type myfunctype: function(c: count);
+
+global global_with_same_name = 100;
+
+global pong: event(msg: string, f: myfunctype);
+
+# This is one, of many, ways to declare your functions that you plan to receive.
+# All you are doing is giving the parser a version of their body, so they can be
+# anywhere. This seems to work quite nicely because it keeps them scoped and stops
+# them from ever being evaluated.
+function my_funcs()
+    {
+    return;
+
+    local begin = 100;
+    local event_count = begin;
+
+    local l : myfunctype = function[event_count](c: count) : function(d: count) : count
+    {
+    print fmt("inside: %s | outside: %s | global: %s", c, event_count, global_with_same_name);
+    return function[c](d: count) : count { return d + c; };
+    };
+
+    local dog_fish = function [begin](base_step : count) : function (step : count) : count
+        {
+# actual formatting doesn't matter for name resolution.
+print fmt("begin: %s | base_step: %s", begin, base_step);
+        return function [begin, base_step](step : count) : count
+            {
+                        print fmt("begin: %s | base_step: %s | step: %s", begin, base_step, step);
+                        return (begin += base_step + step); }; };
+        }
+
+event zeek_init()
+    {
+    print "hello :-)";
+    Broker::subscribe("zeek/event/my_topic");
+    Broker::listen("127.0.0.1", to_port(getenv("BROKER_PORT")));
+    }
+
+event Broker::peer_added(endpoint: Broker::EndpointInfo, msg: string)
+    {
+    print "peer added";
+    }
+
+event Broker::peer_lost(endpoint: Broker::EndpointInfo, msg: string)
+    {
+    print "peer lost";
+    }
+
+global n = 0;
+
+event ping(msg: string, f: myfunctype)
+    {
+    print fmt("receiver got ping: %s", msg);
+    ++n;
+    local adder = f(n);
+    print adder(76);
+
+    if ( n == events_to_recv )
+        {
+        terminate();
+        }
+    else
+        {
+        local e = Broker::make_event(pong, msg, f);
+        Broker::publish("zeek/event/my_topic", e);
+        }
+    }
+
+@TEST-END-FILE