diff --git a/ui/components/component-library/box/box.tsx b/ui/components/component-library/box/box.tsx
index 409b0b640..d09d0a6d6 100644
--- a/ui/components/component-library/box/box.tsx
+++ b/ui/components/component-library/box/box.tsx
@@ -130,7 +130,7 @@ const generateClassNames = memoize(
     }
     return classNamesObject;
   },
-  (styleDeclaration, value) => [styleDeclaration, value],
+  (styleDeclaration, value) => `${styleDeclaration}${value}`,
 );
 
 export const Box: BoxComponent = React.forwardRef(
diff --git a/ui/components/ui/box/box.js b/ui/components/ui/box/box.js
index 869413663..679dfb95c 100644
--- a/ui/components/ui/box/box.js
+++ b/ui/components/ui/box/box.js
@@ -184,7 +184,7 @@ const generateClassNames = memoize(
     }
     return classesObject;
   },
-  (type, value) => [type, value],
+  (type, value) => `${type}${value}`,
 );
 
 /**