diff --git a/eleventy.config.js b/eleventy.config.js
index 38b6912..2a68590 100644
--- a/eleventy.config.js
+++ b/eleventy.config.js
@@ -27,7 +27,7 @@ const IMAGE_TRANSFORM_OPTS = {
   defaultAttributes: {
     loading: 'lazy',
     decoding: 'async',
-    sizes: IMAGE_ATTR_SIZES.map(({ minw, size }) => (minw ? `(min-width: ${minw}): ${size}` : size))
+    sizes: IMAGE_ATTR_SIZES.map(({ minw, size }) => (minw ? `(min-width: ${minw}) ${size}` : size)).join(', ')
   }
 };