diff --git a/src/common.js b/src/common.js
index 0b6d0b64..2f82b8dc 100644
--- a/src/common.js
+++ b/src/common.js
@@ -143,7 +143,9 @@ function setup(env) {
 	}
 
 	function extend(namespace, delimiter) {
-		return createDebug(this.namespace + (typeof delimiter === 'undefined' ? ':' : delimiter) + namespace);
+		const newDebug = createDebug(this.namespace + (typeof delimiter === 'undefined' ? ':' : delimiter) + namespace);
+		newDebug.log = this.log;
+		return newDebug;
 	}
 
 	/**
diff --git a/test.js b/test.js
index 888f9bd8..d8ffca4e 100644
--- a/test.js
+++ b/test.js
@@ -80,6 +80,14 @@ describe('debug', () => {
 			const logBar = log.extend('bar', '');
 			expect(logBar.namespace).to.be.equal('foobar');
 		});
+
+		it('should keep the log function between extensions', () => {
+			const log = debug('foo');
+			log.log = () => {};
+
+			const logBar = log.extend('bar');
+			expect(log.log).to.be.equal(logBar.log);
+		});
 	});
 
 	describe('rebuild namespaces string (disable)', () => {