diff --git a/core/array/fetch_spec.rb b/core/array/fetch_spec.rb
index b81c0b48d..598b481ba 100644
--- a/core/array/fetch_spec.rb
+++ b/core/array/fetch_spec.rb
@@ -12,9 +12,9 @@
   end
 
   it "raises an IndexError if there is no element at index" do
-    -> { [1, 2, 3].fetch(3) }.should raise_error(IndexError)
-    -> { [1, 2, 3].fetch(-4) }.should raise_error(IndexError)
-    -> { [].fetch(0) }.should raise_error(IndexError)
+    -> { [1, 2, 3].fetch(3) }.should raise_error(IndexError, "index 3 outside of array bounds: -3...3")
+    -> { [1, 2, 3].fetch(-4) }.should raise_error(IndexError, "index -4 outside of array bounds: -3...3")
+    -> { [].fetch(0) }.should raise_error(IndexError, "index 0 outside of array bounds: 0...0")
   end
 
   it "returns default if there is no element at index if passed a default value" do
@@ -50,6 +50,6 @@ def o.to_int(); 5; end
   end
 
   it "raises a TypeError when the passed argument can't be coerced to Integer" do
-    -> { [].fetch("cat") }.should raise_error(TypeError)
+    -> { [].fetch("cat") }.should raise_error(TypeError, "no implicit conversion of String into Integer")
   end
 end