diff --git a/packages/block-editor/src/components/spacing-sizes-control/test/utils.js b/packages/block-editor/src/components/spacing-sizes-control/test/utils.js
index d6b2fa2b4850bd..a631cbfcff3ef1 100644
--- a/packages/block-editor/src/components/spacing-sizes-control/test/utils.js
+++ b/packages/block-editor/src/components/spacing-sizes-control/test/utils.js
@@ -49,7 +49,15 @@ describe( 'getCustomValueFromPreset', () => {
 } );
 
 describe( 'getPresetValueFromCustomValue', () => {
-	const spacingSizes = [ { name: 'Small', slug: 20, size: '8px' } ];
+	const spacingSizes = [
+		{ name: 'Default', slug: 'default', size: undefined },
+		{ name: 'Small', slug: 20, size: '8px' },
+	];
+	it( 'should return undefined even if an undefined value exist in spacing sizes as occurs if spacingSizes has > 7 entries', () => {
+		expect( getPresetValueFromCustomValue( undefined, spacingSizes ) ).toBe(
+			undefined
+		);
+	} );
 	it( 'should return original value if a string in spacing presets var format', () => {
 		expect(
 			getPresetValueFromCustomValue(
diff --git a/packages/block-editor/src/components/spacing-sizes-control/utils.js b/packages/block-editor/src/components/spacing-sizes-control/utils.js
index 340abb0322e9a2..7ca0e1b6f660fd 100644
--- a/packages/block-editor/src/components/spacing-sizes-control/utils.js
+++ b/packages/block-editor/src/components/spacing-sizes-control/utils.js
@@ -101,8 +101,8 @@ export function getCustomValueFromPreset( value, spacingSizes ) {
  * @return {string} The preset value if it can be found.
  */
 export function getPresetValueFromCustomValue( value, spacingSizes ) {
-	// Return value as-is if it is already a preset;
-	if ( isValueSpacingPreset( value ) || value === '0' ) {
+	// Return value as-is if it is undefined or is already a preset, or '0';
+	if ( ! value || isValueSpacingPreset( value ) || value === '0' ) {
 		return value;
 	}