diff --git a/blocks/library/heading/index.js b/blocks/library/heading/index.js
index ff673288bc65f2..493697fd23bb55 100644
--- a/blocks/library/heading/index.js
+++ b/blocks/library/heading/index.js
@@ -62,8 +62,14 @@ registerBlockType( 'core/heading', {
 				type: 'raw',
 				source: ( node ) => /H\d/.test( node.nodeName ),
 				attributes: {
-					content: children( 'h1,h2,h3,h4,h5,h6' ),
-					nodeName: prop( 'h1,h2,h3,h4,h5,h6', 'nodeName' ),
+					content: {
+						type: 'array',
+						source: children( 'h1,h2,h3,h4,h5,h6' ),
+					},
+					nodeName: {
+						type: 'string',
+						source: prop( 'h1,h2,h3,h4,h5,h6', 'nodeName' ),
+					},
 				},
 			},
 			{
diff --git a/blocks/library/image/index.js b/blocks/library/image/index.js
index c52e584e6cebbf..26b6aaf1eeb487 100644
--- a/blocks/library/image/index.js
+++ b/blocks/library/image/index.js
@@ -79,9 +79,18 @@ registerBlockType( 'core/image', {
 					( ! node.textContent && node.querySelector( 'img' ) )
 				),
 				attributes: {
-					url: attr( 'img', 'src' ),
-					alt: attr( 'img', 'alt' ),
-					caption: children( 'figcaption' ),
+					url: {
+						type: 'string',
+						source: attr( 'img', 'src' ),
+					},
+					alt: {
+						type: 'string',
+						source: attr( 'img', 'alt' ),
+					},
+					caption: {
+						type: 'array',
+						source: children( 'figcaption' ),
+					},
 				},
 			},
 		],
diff --git a/blocks/library/list/index.js b/blocks/library/list/index.js
index 8de0508ff6057d..4977f4ef6dae90 100644
--- a/blocks/library/list/index.js
+++ b/blocks/library/list/index.js
@@ -124,8 +124,15 @@ registerBlockType( 'core/list', {
 				type: 'raw',
 				source: ( node ) => node.nodeName === 'OL' || node.nodeName === 'UL',
 				attributes: {
-					nodeName: prop( 'ol,ul', 'nodeName' ),
-					values: children( 'ol,ul' ),
+					nodeName: {
+						type: 'string',
+						source: prop( 'ol,ul', 'nodeName' ),
+					},
+					values: {
+						type: 'array',
+						source: children( 'ol,ul' ),
+						default: [],
+					},
 				},
 			},
 			{
diff --git a/blocks/library/paragraph/index.js b/blocks/library/paragraph/index.js
index 57dfa2b42e1bf3..880cb72f64aede 100644
--- a/blocks/library/paragraph/index.js
+++ b/blocks/library/paragraph/index.js
@@ -56,7 +56,10 @@ registerBlockType( 'core/paragraph', {
 					! node.querySelector( 'audio, canvas, embed, iframe, img, math, object, svg, video' )
 				),
 				attributes: {
-					content: children( 'p' ),
+					content: {
+						type: 'array',
+						source: children( 'p' ),
+					},
 				},
 			},
 		],