diff --git a/exercises/primitive_types/primitive_types1.rs b/exercises/primitive_types/primitive_types1.rs
index 0912139..de0d08a 100644
--- a/exercises/primitive_types/primitive_types1.rs
+++ b/exercises/primitive_types/primitive_types1.rs
@@ -4,6 +4,7 @@
 
 // I AM NOT DONE
 
+#[test]
 fn main() {
     // Booleans (`bool`)
 
diff --git a/exercises/primitive_types/primitive_types2.rs b/exercises/primitive_types/primitive_types2.rs
index 6576a4d..8730baa 100644
--- a/exercises/primitive_types/primitive_types2.rs
+++ b/exercises/primitive_types/primitive_types2.rs
@@ -7,6 +7,8 @@
 fn main() {
     // Characters (`char`)
 
+    // Note the _single_ quotes, these are different from the double quotes
+    // you've been seeing around.
     let my_first_initial = 'C';
     if my_first_initial.is_alphabetic() {
         println!("Alphabetical!");
diff --git a/exercises/primitive_types/primitive_types3.rs b/exercises/primitive_types/primitive_types3.rs
index aaa518b..fa7d019 100644
--- a/exercises/primitive_types/primitive_types3.rs
+++ b/exercises/primitive_types/primitive_types3.rs
@@ -1,6 +1,6 @@
 // primitive_types3.rs
 // Create an array with at least 100 elements in it where the ??? is.
-// Execute `rustlings hint primitive_types3` for hints!
+// Execute `rustlings hint primitive_types3` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE
 
diff --git a/exercises/primitive_types/primitive_types4.rs b/exercises/primitive_types/primitive_types4.rs
index 10b553e..71fa243 100644
--- a/exercises/primitive_types/primitive_types4.rs
+++ b/exercises/primitive_types/primitive_types4.rs
@@ -1,6 +1,6 @@
 // primitive_types4.rs
 // Get a slice out of Array a where the ??? is so that the test passes.
-// Execute `rustlings hint primitive_types4` for hints!!
+// Execute `rustlings hint primitive_types4` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE
 
diff --git a/exercises/primitive_types/primitive_types5.rs b/exercises/primitive_types/primitive_types5.rs
index 680d8d2..4fd9141 100644
--- a/exercises/primitive_types/primitive_types5.rs
+++ b/exercises/primitive_types/primitive_types5.rs
@@ -1,6 +1,6 @@
 // primitive_types5.rs
 // Destructure the `cat` tuple so that the println will work.
-// Execute `rustlings hint primitive_types5` for hints!
+// Execute `rustlings hint primitive_types5` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE