diff --git a/packages/govuk-frontend/src/govuk/all.mjs b/packages/govuk-frontend/src/govuk/all.mjs
index eb322df5d3..86bfb13f74 100644
--- a/packages/govuk-frontend/src/govuk/all.mjs
+++ b/packages/govuk-frontend/src/govuk/all.mjs
@@ -48,7 +48,7 @@ function initAll(config) {
 
   // Allow the user to initialise GOV.UK Frontend in only certain sections of the page
   // Defaults to the entire document if nothing is set.
-  const $scope = config.scope || document
+  const $scope = config.scope ?? document
 
   components.forEach(([Component, config]) => {
     const $elements = $scope.querySelectorAll(
diff --git a/packages/govuk-frontend/src/govuk/components/character-count/character-count.mjs b/packages/govuk-frontend/src/govuk/components/character-count/character-count.mjs
index c4623dfe0e..2ba9564544 100644
--- a/packages/govuk-frontend/src/govuk/components/character-count/character-count.mjs
+++ b/packages/govuk-frontend/src/govuk/components/character-count/character-count.mjs
@@ -128,7 +128,7 @@ export class CharacterCount extends GOVUKFrontendComponent {
     })
 
     // Determine the limit attribute (characters or words)
-    this.maxLength = this.config.maxwords || this.config.maxlength || Infinity
+    this.maxLength = this.config.maxwords ?? this.config.maxlength ?? Infinity
 
     this.$module = $module
     this.$textarea = $textarea
@@ -344,7 +344,7 @@ export class CharacterCount extends GOVUKFrontendComponent {
    */
   count(text) {
     if (this.config.maxwords) {
-      const tokens = text.match(/\S+/g) || [] // Matches consecutive non-whitespace chars
+      const tokens = text.match(/\S+/g) ?? [] // Matches consecutive non-whitespace chars
       return tokens.length
     } else {
       return text.length
diff --git a/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.mjs b/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.mjs
index fa92fe03e5..ac8c9c50d5 100644
--- a/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.mjs
+++ b/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.mjs
@@ -187,7 +187,7 @@ export class ErrorSummary extends GOVUKFrontendComponent {
     }
 
     return (
-      document.querySelector(`label[for='${$input.getAttribute('id')}']`) ||
+      document.querySelector(`label[for='${$input.getAttribute('id')}']`) ??
       $input.closest('label')
     )
   }
diff --git a/packages/govuk-frontend/src/govuk/components/tabs/tabs.mjs b/packages/govuk-frontend/src/govuk/components/tabs/tabs.mjs
index 255d8bb59d..29d6b5f2cb 100644
--- a/packages/govuk-frontend/src/govuk/components/tabs/tabs.mjs
+++ b/packages/govuk-frontend/src/govuk/components/tabs/tabs.mjs
@@ -162,7 +162,7 @@ export class Tabs extends GOVUKFrontendComponent {
     })
 
     // Show either the active tab according to the URL's hash or the first tab
-    const $activeTab = this.getTab(window.location.hash) || this.$tabs[0]
+    const $activeTab = this.getTab(window.location.hash) ?? this.$tabs[0]
 
     this.showTab($activeTab)
 
diff --git a/packages/govuk-frontend/src/govuk/errors/index.mjs b/packages/govuk-frontend/src/govuk/errors/index.mjs
index 17dea86d6a..71cbe86e61 100644
--- a/packages/govuk-frontend/src/govuk/errors/index.mjs
+++ b/packages/govuk-frontend/src/govuk/errors/index.mjs
@@ -76,7 +76,7 @@ export class ElementError extends GOVUKFrontendError {
 
       // Append reason
       message += element
-        ? ` is not of type ${expectedType || 'HTMLElement'}`
+        ? ` is not of type ${expectedType ?? 'HTMLElement'}`
         : ' not found'
     }
 
diff --git a/packages/govuk-frontend/src/govuk/i18n.mjs b/packages/govuk-frontend/src/govuk/i18n.mjs
index 77fc164048..d0632db1f1 100644
--- a/packages/govuk-frontend/src/govuk/i18n.mjs
+++ b/packages/govuk-frontend/src/govuk/i18n.mjs
@@ -19,7 +19,7 @@ export class I18n {
     this.translations = translations
 
     // The locale to use for PluralRules and NumberFormat
-    this.locale = config.locale || document.documentElement.lang || 'en'
+    this.locale = config.locale ?? (document.documentElement.lang || 'en')
   }
 
   /**