diff --git a/src/Type.cc b/src/Type.cc
index 810a08b443..85e057137f 100644
--- a/src/Type.cc
+++ b/src/Type.cc
@@ -900,6 +900,45 @@ void RecordType::Describe(ODesc* d) const
 		}
 	}
 
+const char* RecordType::AddFields(type_decl_list* others, attr_list* attr)
+	{
+	assert(types);
+
+	bool log = false;
+
+	if ( attr )
+		{
+		loop_over_list(*attr, j)
+			{
+			if ( (*attr)[j]->Tag() == ATTR_LOG )
+				log = true;
+			}
+		}
+	
+	loop_over_list(*others, i)
+		{
+		TypeDecl* td = (*others)[i];
+
+		if ( ! td->FindAttr(ATTR_DEFAULT) && ! td->FindAttr(ATTR_OPTIONAL) )
+			return "extension field must be &optional or have &default";
+
+		if ( log )
+			{
+			if ( ! td->attrs )
+				td->attrs = new Attributes(new attr_list, td->type);
+
+			td->attrs->AddAttr(new Attr(ATTR_LOG));
+			}
+
+		types->append(td);
+		}
+
+	delete others;
+
+	num_fields = types->length();
+	return 0;
+	}
+
 void RecordType::DescribeFields(ODesc* d) const
 	{
 	if ( d->IsReadable() )
diff --git a/src/Type.h b/src/Type.h
index b93fcaa6d7..eccfecb89e 100644
--- a/src/Type.h
+++ b/src/Type.h
@@ -437,6 +437,10 @@ public:
 
 	int NumFields() const			{ return num_fields; }
 
+	// Returns 0 if all is ok, otherwise a pointer to an error message. Takes
+	// ownership of list.
+	const char* AddFields(type_decl_list* types, attr_list* attr);
+
 	void Describe(ODesc* d) const;
 	void DescribeFields(ODesc* d) const;
 
diff --git a/src/parse.y b/src/parse.y
index 18ccfff202..15d75341a1 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -862,7 +862,25 @@ decl:
 		'{' { parser_redef_enum($3); } enum_body '}' ';'
 			{ /* no action */ }
 
-	|	TOK_TYPE def_global_id ':' refined_type opt_attr ';'
+	|	TOK_REDEF TOK_RECORD global_id TOK_ADD_TO
+			'{' type_decl_list '}' opt_attr ';'
+			{
+			if ( ! $3->Type() )
+				$3->Error("unknown identifier");
+			else
+				{
+				RecordType* add_to = $3->Type()->AsRecordType();
+				if ( ! add_to )
+					$3->Error("not a record type");
+				else {
+					const char* error = add_to->AddFields($6, $8);
+					if ( error )
+    					$3->Error(error);
+				}
+			}
+    	}
+
+	|	TOK_TYPE global_id ':' refined_type opt_attr ';'
 			{
 			add_type($2, $4, $5, 0);
 			}
diff --git a/testing/btest/Baseline/logging.attr-extend/ssh.log b/testing/btest/Baseline/logging.attr-extend/ssh.log
new file mode 100644
index 0000000000..d543af3a43
--- /dev/null
+++ b/testing/btest/Baseline/logging.attr-extend/ssh.log
@@ -0,0 +1,2 @@
+# status	country	a1	b1	b2
+success	unknown	1	3	4
diff --git a/testing/btest/logging/attr-extend.bro b/testing/btest/logging/attr-extend.bro
index f6964a749e..4d7e96b98e 100644
--- a/testing/btest/logging/attr-extend.bro
+++ b/testing/btest/logging/attr-extend.bro
@@ -15,14 +15,14 @@ export {
 	};
 }
 
-redef Log += record {
-	a1: count &log;
-	a2: count;
+redef record Log += {
+	a1: count &log &optional;
+	a2: count &optional;
 };
 
-redef Log += record {
-	b1: count;
-	b2: count;
+redef record Log += {
+	b1: count &optional;
+	b2: count &optional;
 } &log;
 
 
@@ -32,6 +32,6 @@ event bro_init()
 
     local cid = [$orig_h=1.2.3.4, $orig_p=1234/tcp, $resp_h=2.3.4.5, $resp_p=80/tcp];
 
-	Log::write(SSH, [$t=network_time(), $id=cid, $status="success", a1=1, a2=2, a3=3, a4=4]);
+	Log::write(SSH, [$t=network_time(), $id=cid, $status="success", $a1=1, $a2=2, $b1=3, $b2=4]);
 }
 
diff --git a/testing/rec.bro b/testing/rec.bro
new file mode 100644
index 0000000000..904edd4e8c
--- /dev/null
+++ b/testing/rec.bro
@@ -0,0 +1,17 @@
+# @TEST-EXEC: bro %INPUT >output
+# @TEST-EXEC: btest-diff output
+
+type Foo: record {
+        a: count;
+        b: count &optional;
+};
+
+redef record Foo += {
+        c: count &default=42;
+        d: count &optional;
+};
+
+global f: Foo = [$a=21];
+
+print f;
+
diff --git a/testing/rec2.bro b/testing/rec2.bro
new file mode 100644
index 0000000000..c8324ae577
--- /dev/null
+++ b/testing/rec2.bro
@@ -0,0 +1,17 @@
+# @TEST-EXEC: bro %INPUT >output
+# @TEST-EXEC: btest-diff output
+
+type Foo: record {
+        a: count;
+        b: count &optional;
+};
+
+redef record Foo += {
+        c: count &default=42;
+        d: string &optional;
+};
+
+global f: Foo = [$a=21, $d="XXX"];
+
+print f;
+
diff --git a/testing/wrong-rec.bro b/testing/wrong-rec.bro
new file mode 100644
index 0000000000..e5f553bf45
--- /dev/null
+++ b/testing/wrong-rec.bro
@@ -0,0 +1,13 @@
+# @TEST-EXEC-FAIL: bro %INPUT >output 2>&1
+# @TEST-EXEC: btest-diff output
+
+type Foo: record {
+        a: count;
+        b: count &optional;
+};
+
+redef record Foo += {
+        c: count;
+        d: string &optional;
+};
+