diff --git a/exercises/practice/luhn/.docs/instructions.md b/exercises/practice/luhn/.docs/instructions.md
index df2e304a3..7702c6bbb 100644
--- a/exercises/practice/luhn/.docs/instructions.md
+++ b/exercises/practice/luhn/.docs/instructions.md
@@ -41,7 +41,7 @@ If the sum is evenly divisible by 10, the original number is valid.
 
 ### Invalid Canadian SIN
 
-The number to be checked is `066 123 468`.
+The number to be checked is `066 123 478`.
 
 We start at the end of the number and double every second digit, beginning with the second digit from the right and moving left.
 
diff --git a/exercises/practice/piecing-it-together/.meta/config.json b/exercises/practice/piecing-it-together/.meta/config.json
index 76e6e6cbf..b58751cb9 100644
--- a/exercises/practice/piecing-it-together/.meta/config.json
+++ b/exercises/practice/piecing-it-together/.meta/config.json
@@ -14,6 +14,9 @@
     ],
     "editor": [
       "src/main/java/JigsawInfo.java"
+    ],
+    "invalidator": [
+      "build.gradle"
     ]
   },
   "blurb": "Fill in missing jigsaw puzzle details from partial data",