diff --git a/src/components/sprite-selector-item/sprite-selector-item.jsx b/src/components/sprite-selector-item/sprite-selector-item.jsx
index 9dae616fef37ee0241d693fe5c4c17f86739c201..648248514f5dfad010266c7c11579626825cdf69 100644
--- a/src/components/sprite-selector-item/sprite-selector-item.jsx
+++ b/src/components/sprite-selector-item/sprite-selector-item.jsx
@@ -64,7 +64,7 @@ SpriteSelectorItem.propTypes = {
     costumeURL: PropTypes.string,
     name: PropTypes.string.isRequired,
     onClick: PropTypes.func,
-    onDeleteButtonClick: PropTypes.func,
+    onDeleteButtonClick: PropTypes.func.isRequired,
     onDuplicateButtonClick: PropTypes.func,
     selected: PropTypes.bool.isRequired
 };
diff --git a/src/containers/sprite-selector-item.jsx b/src/containers/sprite-selector-item.jsx
index 7b38825a1aa4ddfb60023b2df912b14ee866a75e..0bc01382cac731a6bcef3b52a16fe4fb4c2d757b 100644
--- a/src/containers/sprite-selector-item.jsx
+++ b/src/containers/sprite-selector-item.jsx
@@ -57,7 +57,7 @@ SpriteSelectorItem.propTypes = {
     id: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
     name: PropTypes.string,
     onClick: PropTypes.func,
-    onDeleteButtonClick: PropTypes.func,
+    onDeleteButtonClick: PropTypes.func.isRequired,
     onDuplicateButtonClick: PropTypes.func,
     selected: PropTypes.bool
 };