diff --git a/lib/block-supports/typography.php b/lib/block-supports/typography.php
index bdcb2bbe98896..c4e1316ac3893 100644
--- a/lib/block-supports/typography.php
+++ b/lib/block-supports/typography.php
@@ -468,7 +468,7 @@ function gutenberg_get_typography_font_size_value( $preset, $should_use_fluid_ty
 
 	// Defaults overrides.
 	$minimum_viewport_width = isset( $fluid_settings['minViewportWidth'] ) ? $fluid_settings['minViewportWidth'] : $default_minimum_viewport_width;
-	$maximum_viewport_width = isset( $layout_settings['wideSize'] ) ? $layout_settings['wideSize'] : $default_maximum_viewport_width;
+	$maximum_viewport_width = isset( $layout_settings['wideSize'] ) && ! empty( gutenberg_get_typography_value_and_unit( $layout_settings['wideSize'] ) ) ? $layout_settings['wideSize'] : $default_maximum_viewport_width;
 	if ( isset( $fluid_settings['maxViewportWidth'] ) ) {
 		$maximum_viewport_width = $fluid_settings['maxViewportWidth'];
 	}
diff --git a/packages/block-editor/src/components/global-styles/typography-utils.js b/packages/block-editor/src/components/global-styles/typography-utils.js
index c88019adc38dd..cd1340033e377 100644
--- a/packages/block-editor/src/components/global-styles/typography-utils.js
+++ b/packages/block-editor/src/components/global-styles/typography-utils.js
@@ -7,7 +7,10 @@
 /**
  * Internal dependencies
  */
-import { getComputedFluidTypographyValue } from '../font-sizes/fluid-utils';
+import {
+	getComputedFluidTypographyValue,
+	getTypographyValueAndUnit,
+} from '../font-sizes/fluid-utils';
 
 /**
  * @typedef {Object} FluidPreset
@@ -99,11 +102,16 @@ function isFluidTypographyEnabled( typographySettings ) {
 export function getFluidTypographyOptionsFromSettings( settings ) {
 	const typographySettings = settings?.typography;
 	const layoutSettings = settings?.layout;
-	return isFluidTypographyEnabled( typographySettings ) &&
+	const defaultMaxViewportWidth = getTypographyValueAndUnit(
 		layoutSettings?.wideSize
+	)
+		? layoutSettings?.wideSize
+		: null;
+	return isFluidTypographyEnabled( typographySettings ) &&
+		defaultMaxViewportWidth
 		? {
 				fluid: {
-					maxViewportWidth: layoutSettings.wideSize,
+					maxViewportWidth: defaultMaxViewportWidth,
 					...typographySettings.fluid,
 				},
 		  }