diff --git a/mithril.js b/mithril.js
index ad11edbe..708089c1 100644
--- a/mithril.js
+++ b/mithril.js
@@ -347,12 +347,14 @@ Mithril = m = new function app(window) {
 		var resolvers = [], rejecters = [], resolved, rejected
 		var object = {
 			resolve: function(value) {
-				resolved = value
+				if (resolved === undefined) resolved = value
 				for (var i = 0; i < resolvers.length; i++) resolvers[i](value)
+				resolvers.length = rejecters.length = 0
 			},
 			reject: function(value) {
-				rejected = value
+				if (rejected === undefined) rejected = value
 				for (var i = 0; i < rejecters.length; i++) rejecters[i](value)
+				resolvers.length = rejecters.length = 0
 			},
 			promise: m.prop()
 		}
diff --git a/tests/mithril-tests.js b/tests/mithril-tests.js
index d6c315d8..7c836372 100644
--- a/tests/mithril-tests.js
+++ b/tests/mithril-tests.js
@@ -688,6 +688,60 @@ function testMithril(mock) {
 		})
 		return value === 1
 	})
+	test(function() {
+		//https://github.com/lhorie/mithril.js/issues/80
+		var deferred = m.deferred(), value
+		deferred.resolve(1)
+		deferred.resolve(2)
+		deferred.promise.then(function(data) {
+			value = data
+		})
+		return value === 1
+	})
+	test(function() {
+		//https://github.com/lhorie/mithril.js/issues/80
+		var deferred = m.deferred(), value
+		deferred.promise.then(function(data) {
+			value = data
+		})
+		deferred.resolve(1)
+		deferred.resolve(2)
+		return value === 1
+	})
+	test(function() {
+		//https://github.com/lhorie/mithril.js/issues/80
+		var deferred = m.deferred(), value1, value2
+		deferred.promise.then(function(data) {
+			value1 = data
+		}, function(data) {
+			value2 = data
+		})
+		deferred.resolve(1)
+		deferred.reject(2)
+		return value1 === 1 && value2 === undefined
+	})
+	test(function() {
+		//https://github.com/lhorie/mithril.js/issues/80
+		var deferred = m.deferred(), value1, value2
+		deferred.promise.then(function() {
+			value1 = data
+		}, function(data) {
+			value2 = data
+		})
+		deferred.reject(1)
+		deferred.resolve(2)
+		return value1 === undefined && value2 === 1
+	})
+	test(function() {
+		//https://github.com/lhorie/mithril.js/issues/80
+		var deferred = m.deferred(), value
+		deferred.promise.then(null, function(data) {
+			value = data
+		})
+		deferred.reject(1)
+		deferred.reject(2)
+		return value === 1
+	})
 
 	//m.sync
 	test(function() {