diff --git a/listings/ch11-writing-automated-tests/listing-11-01/src/lib.rs b/listings/ch11-writing-automated-tests/listing-11-01/src/lib.rs
index 1b4a90c938..7d12d9af81 100644
--- a/listings/ch11-writing-automated-tests/listing-11-01/src/lib.rs
+++ b/listings/ch11-writing-automated-tests/listing-11-01/src/lib.rs
@@ -1,8 +1,14 @@
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     #[test]
     fn it_works() {
-        let result = 2 + 2;
+        let result = add(2, 2);
         assert_eq!(result, 4);
     }
 }
diff --git a/listings/ch11-writing-automated-tests/listing-11-03/output.txt b/listings/ch11-writing-automated-tests/listing-11-03/output.txt
index 2fa5cf0774..d748b19fe1 100644
--- a/listings/ch11-writing-automated-tests/listing-11-03/output.txt
+++ b/listings/ch11-writing-automated-tests/listing-11-03/output.txt
@@ -10,7 +10,7 @@ test tests::exploration ... ok
 failures:
 
 ---- tests::another stdout ----
-thread 'main' panicked at 'Make this test fail', src/lib.rs:10:9
+thread 'main' panicked at 'Make this test fail', src/lib.rs:17:9
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 
 
diff --git a/listings/ch11-writing-automated-tests/listing-11-03/src/lib.rs b/listings/ch11-writing-automated-tests/listing-11-03/src/lib.rs
index a9ec008919..0db269085f 100644
--- a/listings/ch11-writing-automated-tests/listing-11-03/src/lib.rs
+++ b/listings/ch11-writing-automated-tests/listing-11-03/src/lib.rs
@@ -1,9 +1,16 @@
 // ANCHOR: here
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     #[test]
     fn exploration() {
-        assert_eq!(2 + 2, 4);
+        let result = add(2, 2);
+        assert_eq!(result, 4);
     }
 
     #[test]
diff --git a/listings/ch11-writing-automated-tests/no-listing-01-changing-test-name/src/lib.rs b/listings/ch11-writing-automated-tests/no-listing-01-changing-test-name/src/lib.rs
index 330bddf6ac..5be58b93fc 100644
--- a/listings/ch11-writing-automated-tests/no-listing-01-changing-test-name/src/lib.rs
+++ b/listings/ch11-writing-automated-tests/no-listing-01-changing-test-name/src/lib.rs
@@ -1,7 +1,14 @@
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     #[test]
     fn exploration() {
-        assert_eq!(2 + 2, 4);
+        let result = add(2, 2);
+        assert_eq!(result, 4);
     }
 }
diff --git a/listings/ch11-writing-automated-tests/no-listing-10-result-in-tests/src/lib.rs b/listings/ch11-writing-automated-tests/no-listing-10-result-in-tests/src/lib.rs
index 6284f4f291..5db22b89b9 100644
--- a/listings/ch11-writing-automated-tests/no-listing-10-result-in-tests/src/lib.rs
+++ b/listings/ch11-writing-automated-tests/no-listing-10-result-in-tests/src/lib.rs
@@ -1,8 +1,14 @@
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     #[test]
     fn it_works() -> Result<(), String> {
-        if 2 + 2 == 4 {
+        if add(2, 2) == 4 {
             Ok(())
         } else {
             Err(String::from("two plus two does not equal four"))
diff --git a/listings/ch14-more-about-cargo/output-only-02-add-one/add/add_one/src/lib.rs b/listings/ch14-more-about-cargo/output-only-02-add-one/add/add_one/src/lib.rs
index 1b4a90c938..2ecdc793cf 100644
--- a/listings/ch14-more-about-cargo/output-only-02-add-one/add/add_one/src/lib.rs
+++ b/listings/ch14-more-about-cargo/output-only-02-add-one/add/add_one/src/lib.rs
@@ -1,8 +1,14 @@
+fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     #[test]
     fn it_works() {
-        let result = 2 + 2;
+        let result = add(2, 2);
         assert_eq!(result, 4);
     }
 }
diff --git a/nostarch/chapter11.md b/nostarch/chapter11.md
index cf909d70c5..0e6d7e3d92 100644
--- a/nostarch/chapter11.md
+++ b/nostarch/chapter11.md
@@ -172,11 +172,17 @@ the `it_works` function to a different name, such as `exploration`, like so:
 Filename: src/lib.rs
 
 ```
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     #[test]
     fn exploration() {
-        let result = 2 + 2;
+        let result = add(2, 2);
         assert_eq!(result, 4);
     }
 }
@@ -203,11 +209,18 @@ is to call the `panic!` macro. Enter the new test as a function named
 Filename: src/lib.rs
 
 ```
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     #[test]
     fn exploration() {
-        assert_eq!(2 + 2, 4);
+        let result = add(2, 2);
+        assert_eq!(result, 4);
     }
 
     #[test]
@@ -231,7 +244,7 @@ test tests::exploration ... ok
 2 failures:
 
 ---- tests::another stdout ----
-thread 'main' panicked at 'Make this test fail', src/lib.rs:10:9
+thread 'main' panicked at 'Make this test fail', src/lib.rs:17:9
 note: run with `RUST_BACKTRACE=1` environment variable to display
 a backtrace
 
@@ -867,11 +880,17 @@ E>` and return an `Err` instead of panicking:
 Filename: src/lib.rs
 
 ```
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     #[test]
     fn it_works() -> Result<(), String> {
-        if 2 + 2 == 4 {
+        if add(2, 2) == 4 {
             Ok(())
         } else {
             Err(String::from("two plus two does not equal four"))
@@ -1265,11 +1284,17 @@ this chapter, Cargo generated this code for us:
 Filename: src/lib.rs
 
 ```
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     #[test]
     fn it_works() {
-        let result = 2 + 2;
+        let result = add(2, 2);
         assert_eq!(result, 4);
     }
 }
diff --git a/src/ch11-01-writing-tests.md b/src/ch11-01-writing-tests.md
index df09aadc84..4ab533f9ed 100644
--- a/src/ch11-01-writing-tests.md
+++ b/src/ch11-01-writing-tests.md
@@ -62,16 +62,19 @@ cd ../../..
 <span class="caption">Listing 11-1: The test module and function generated
 automatically by `cargo new`</span>
 
-For now, let’s ignore the top two lines and focus on the function. Note the
+The file starts with an example `add` function, so that we have something
+to test.
+
+For now, let’s ignore the next few lines and focus on the function with the
 `#[test]` annotation: this attribute indicates this is a test function, so the
 test runner knows to treat this function as a test. We might also have non-test
 functions in the `tests` module to help set up common scenarios or perform
 common operations, so we always need to indicate which functions are tests.
 
 The example function body uses the `assert_eq!` macro to assert that `result`,
-which contains the result of adding 2 and 2, equals 4. This assertion serves as
-an example of the format for a typical test. Let’s run it to see that this test
-passes.
+which contains the result of calling `add` with 2 and 2, equals 4. This
+assertion serves as an example of the format for a typical test. Let’s run it
+to see that this test passes.
 
 The `cargo test` command runs all tests in our project, as shown in Listing
 11-2.