diff --git a/src/lib/components/eyebrowHeading.svelte b/src/lib/components/eyebrowHeading.svelte
index f07f8cb87..34bac2185 100644
--- a/src/lib/components/eyebrowHeading.svelte
+++ b/src/lib/components/eyebrowHeading.svelte
@@ -7,7 +7,7 @@
     export let trimmed = true;
     export let id: string = null;
     export let style: string = undefined;
-    let classes: string = undefined;
+    let classes: string = '';
     export { classes as class };
 </script>
 
diff --git a/src/lib/components/secondaryTabs.svelte b/src/lib/components/secondaryTabs.svelte
index 835f1a1cc..974d7efcc 100644
--- a/src/lib/components/secondaryTabs.svelte
+++ b/src/lib/components/secondaryTabs.svelte
@@ -1,7 +1,7 @@
 <script lang="ts">
     export let large = false;
     export let stretch = false;
-    let classes: string = undefined;
+    let classes: string = '';
     export { classes as class };
 </script>
 
diff --git a/src/lib/elements/flag.svelte b/src/lib/elements/flag.svelte
index 9f3aebd8e..d1dfe2849 100644
--- a/src/lib/elements/flag.svelte
+++ b/src/lib/elements/flag.svelte
@@ -7,7 +7,7 @@
     export let width = 40;
     export let height = 30;
     export let quality = 100;
-    let classes: string = undefined;
+    let classes: string = '';
     export { classes as class };
 
     export function getFlag(country: string, width: number, height: number, quality: number) {
diff --git a/src/lib/elements/forms/button.svelte b/src/lib/elements/forms/button.svelte
index 0803c7650..60bb92c68 100644
--- a/src/lib/elements/forms/button.svelte
+++ b/src/lib/elements/forms/button.svelte
@@ -21,7 +21,7 @@
     export let ariaLabel: string = null;
     export let noMargin = false;
     export let event: string = null;
-    let classes: string = undefined;
+    let classes: string = '';
     export { classes as class };
     export let actions: MultiActionArray = [];
     export let submissionLoader = false;