diff --git a/packages/leaner/src/web/classes.js b/packages/leaner/src/web/classes.js
index e62976b..9eb99ed 100644
--- a/packages/leaner/src/web/classes.js
+++ b/packages/leaner/src/web/classes.js
@@ -7,15 +7,17 @@ export function setClasses( element, classes ) {
       if ( Array.isArray( value ) ) {
         element.className = '';
         element.classList.add( ...value );
-      } else {
+      } else if ( value != null ) {
         element.className = value;
+      } else {
+        element.removeAttribute( 'class' );
       }
     } );
   } else if ( isPlainObject( classes ) ) {
     setClassesObject( element, classes );
   } else if ( Array.isArray( classes ) ) {
     setClassesArray( element, classes );
-  } else {
+  } else if ( classes != null ) {
     element.className = classes;
   }
 }
@@ -54,7 +56,7 @@ function setClassesArray( element, classes ) {
       } );
     } else if ( isPlainObject( item ) ) {
       setClassesObject( element, item );
-    } else {
+    } else if ( item != null ) {
       element.classList.add( item );
     }
   }
diff --git a/packages/leaner/src/web/make.js b/packages/leaner/src/web/make.js
index f9148c7..ee21b60 100644
--- a/packages/leaner/src/web/make.js
+++ b/packages/leaner/src/web/make.js
@@ -97,9 +97,9 @@ function setElementProperty( element, key, value ) {
     element.addEventListener( key.substring( 2 ), value );
   } else if ( Properties.has( key ) ) {
     if ( typeof value == 'function' )
-      reactive( value, value => element[ key ] = value );
+      reactive( value, value => element[ key ] = value != null ? value : '' );
     else
-      element[ key ] = value;
+      element[ key ] = value != null ? value : '';
   } else {
     if ( typeof value == 'function' )
       reactive( value, value => setElementAttribute( element, key, value ) );
diff --git a/packages/leaner/src/web/styles.js b/packages/leaner/src/web/styles.js
index 37f1dcc..ec7e107 100644
--- a/packages/leaner/src/web/styles.js
+++ b/packages/leaner/src/web/styles.js
@@ -8,13 +8,15 @@ export function setStyles( element, styles ) {
         element.style = '';
         for ( const [ key, value ] of Object.entries( value ) )
           setStyleProperty( element, key, value );
-      } else {
+      } else if ( value != null ) {
         element.style = value;
+      } else {
+        element.removeAttribute( 'style' );
       }
     } );
   } else if ( isPlainObject( styles ) ) {
     setStylesObject( element, styles );
-  } else {
+  } else if ( styles != null ) {
     element.style = styles;
   }
 }
@@ -22,13 +24,15 @@ export function setStyles( element, styles ) {
 function setStylesObject( element, styles ) {
   for ( const [ key, value ] of Object.entries( styles ) ) {
     if ( typeof value == 'function' )
-      reactive( value, value => element.style[ key ] = value );
+      reactive( value, value => setStyleProperty( element, key, value ) );
     else
       setStyleProperty( element, key, value );
   }
 }
 
 function setStyleProperty( element, key, value ) {
+  if ( value == null )
+    value = '';
   if ( key.startsWith( '--' ) )
     element.style.setProperty( key, value );
   else
diff --git a/packages/leaner/test/web/classes.spec.js b/packages/leaner/test/web/classes.spec.js
index f460d4e..7068de6 100644
--- a/packages/leaner/test/web/classes.spec.js
+++ b/packages/leaner/test/web/classes.spec.js
@@ -10,12 +10,24 @@ describe( 'classes', () => {
     expect( element.className ).toBe( 'btn-primary is-large' );
   } );
 
+  test( 'undefined', () => {
+    const element = make( [ 'button', { type: 'button', class: undefined } ] );
+
+    expect( element.outerHTML ).toBe( '<button type="button"></button>' );
+  } );
+
   test( 'static array', () => {
     const element = make( [ 'button', { type: 'button', class: [ 'btn-primary', 'is-large' ] } ] );
 
     expect( element.className ).toBe( 'btn-primary is-large' );
   } );
 
+  test( 'static array with undefined', () => {
+    const element = make( [ 'button', { type: 'button', class: [ 'btn-primary', 'is-large', undefined ] } ] );
+
+    expect( element.className ).toBe( 'btn-primary is-large' );
+  } );
+
   test( 'dynamic value', () => {
     const [ value, setValue ] = state( 'btn-primary' );
 
diff --git a/packages/leaner/test/web/make.spec.js b/packages/leaner/test/web/make.spec.js
index a410a05..7889233 100644
--- a/packages/leaner/test/web/make.spec.js
+++ b/packages/leaner/test/web/make.spec.js
@@ -47,6 +47,13 @@ describe( 'make()', () => {
     expect( element.value ).toBe( 'hello' );
   } );
 
+  test( 'undefined value', () => {
+    const element = make( [ 'input', { value: undefined } ] );
+
+    expect( element ).toBeInstanceOf( HTMLInputElement );
+    expect( element.value ).toBe( '' );
+  } );
+
   test( 'dynamic content', () => {
     const [ value, setValue ] = state( 'test' );
 
@@ -62,6 +69,13 @@ describe( 'make()', () => {
     expect( element.textContent ).toBe( 'hello' );
   } );
 
+  test( 'undefined content', () => {
+    const element = make( [ 'p', undefined ] );
+
+    expect( element ).toBeInstanceOf( HTMLElement );
+    expect( element.textContent ).toBe( '' );
+  } );
+
   test( 'dynamic attribute', () => {
     const [ value, setValue ] = state( 'test' );
 
@@ -77,6 +91,13 @@ describe( 'make()', () => {
     expect( element.outerHTML ).toBe( '<label for="world">hello</label>' );
   } );
 
+  test( 'undefined attribute', () => {
+    const element = make( [ 'label', { for: undefined }, 'hello' ] );
+
+    expect( element ).toBeInstanceOf( HTMLLabelElement );
+    expect( element.outerHTML ).toBe( '<label>hello</label>' );
+  } );
+
   test( 'remove attribute', () => {
     const [ value, setValue ] = state( 'test' );
 
diff --git a/packages/leaner/test/web/styles.spec.js b/packages/leaner/test/web/styles.spec.js
index 0b1f677..672faa5 100644
--- a/packages/leaner/test/web/styles.spec.js
+++ b/packages/leaner/test/web/styles.spec.js
@@ -10,6 +10,12 @@ describe( 'styles', () => {
     expect( element.style.display ).toBe( 'none' );
   } );
 
+  test( 'undefined', () => {
+    const element = make( [ 'button', { type: 'button', style: undefined } ] );
+
+    expect( element.outerHTML ).toBe( '<button type="button"></button>' );
+  } );
+
   test( 'static object', () => {
     const element = make( [ 'button', { type: 'button', style: { display: 'none' } } ] );
 
@@ -44,5 +50,19 @@ describe( 'styles', () => {
     expect( element.style.display ).toBe( 'inline' );
   } );
 
+  test( 'dynamic object with undefined', () => {
+    const [ value, setValue ] = state( 'none' );
+
+    const element = make( [ 'button', { type: 'button', style: { display: value } } ] );
+
+    expect( element.style.display ).toBe( 'none' );
+
+    setValue( undefined );
+
+    runSchedule();
+
+    expect( element.style.display ).toBe( '' );
+  } );
+
   // NOTE: custom properties cannot be tested because of https://github.com/jsdom/jsdom/issues/1895
 } );