diff --git a/Jakefile.js b/Jakefile.js
index ac89d35c..43eab8b9 100644
--- a/Jakefile.js
+++ b/Jakefile.js
@@ -24,24 +24,42 @@ task('lint', function () {
 
 desc('Combine and compress Leaflet source files');
 task('build', ['lint'], function (compsBase32, buildName) {
-	var name = buildName || 'custom',
-		path = 'dist/leaflet' + (compsBase32 ? '-' + name : '');
+	var pathPart = 'dist/leaflet' + (buildName ? '-' + buildName : ''),
+		srcPath = pathPart + '-src.js',
+		path = pathPart + '.js';
 
 	var files = build.getFiles(compsBase32);
 
 	console.log('Concatenating ' + files.length + ' files...');
 	var content = build.combineFiles(files);
-	console.log('\tUncompressed size: ' + content.length);
 	
-	build.save(path + '-src.js', COPYRIGHT + content);
-	console.log('\tSaved to ' + path);
+	var oldSrc = build.load(srcPath),
+		newSrc = COPYRIGHT + content,
+		srcDelta = build.getSizeDelta(newSrc, oldSrc);
+		
+	console.log('\tUncompressed size: ' + newSrc.length + ' bytes (' + srcDelta + ')');
+		
+	if (newSrc === oldSrc) {
+		console.log('\tNo changes');
+	} else {
+		build.save(srcPath, newSrc);
+		console.log('\tSaved to ' + srcPath);
+	}
 	
 	console.log('Compressing...');
-	var compressed = COPYRIGHT + build.uglify(content);
-	console.log('\tCompressed size: ' + compressed.length);
 
-	build.save(path + '.js', compressed);
-	console.log('\tSaved to ' + path);
+	var oldCompressed = build.load(path),
+		newCompressed = COPYRIGHT + build.uglify(content),
+		delta = build.getSizeDelta(newCompressed, oldCompressed);
+		
+	console.log('\tCompressed size: ' + newCompressed.length + ' bytes (' + delta + ')');
+
+	if (newCompressed === oldCompressed) {
+		console.log('\tNo changes');
+	} else {
+		build.save(path, newCompressed);
+		console.log('\tSaved to ' + path);
+	}
 });
 
 task('default', ['build']);
\ No newline at end of file
diff --git a/build/build.js b/build/build.js
index dff8ab2d..a918d3bd 100644
--- a/build/build.js
+++ b/build/build.js
@@ -37,7 +37,7 @@ exports.getFiles = function (compsBase32) {
 	}
 
 	return files;
-}
+};
 
 exports.uglify = function (code) {
 	var pro = uglifyjs.uglify;
@@ -48,7 +48,7 @@ exports.uglify = function (code) {
 	ast = pro.ast_squeeze_more(ast);
 
 	return pro.gen_code(ast);
-}
+};
 
 exports.combineFiles = function (files) {
 	var content = '';
@@ -56,8 +56,24 @@ exports.combineFiles = function (files) {
 		content += fs.readFileSync(files[i], 'utf8') + '\r\n\r\n';
 	}
 	return content;
-}
+};
 
 exports.save = function (savePath, compressed) {
-	fs.writeFileSync(savePath, compressed, 'utf8');
-}
\ No newline at end of file
+	return fs.writeFileSync(savePath, compressed, 'utf8');
+};
+
+exports.load = function (loadPath) {
+	try {
+		return fs.readFileSync(loadPath, 'utf8');
+	} catch (e) {
+		return null;
+	}
+};
+
+exports.getSizeDelta = function (newContent, oldContent) {
+	if (!oldContent) {
+		return 'new';
+	}
+	var delta = newContent.length - oldContent.length;
+	return (delta >= 0 ? '+' : '') + delta;
+};
\ No newline at end of file