diff --git a/README.md b/README.md
index 259c308..930e627 100644
--- a/README.md
+++ b/README.md
@@ -69,12 +69,13 @@ dotnet test --no-build
 ```
 ~~~
 
-Assert that a commit builds, but that the tests do not succeed (`assert_fails` is a helper function included in `git-check-assertions`):
+Assert that a commit builds, but that the tests do not succeed:
 
 ~~~
 ```git-check-assertions
 dotnet build
-assert_fails dotnet test --no-build
+run dotnet test --no-build
+assert_failure
 ```
 ~~~
 
@@ -83,7 +84,9 @@ Assert that a commit builds, and that the tests fail with exactly the error that
 ~~~
 ```git-check-assertions
 dotnet build
-(assert_fails dotnet test --no-build) | grep "Invalid URL"
+run dotnet test --no-build
+assert_failure
+assert_output --partial "Invalid URL"
 ```
 ~~~
 
@@ -94,6 +97,7 @@ Assert that a commit builds, and that a specific change breaks the tests (as dis
 dotnet test
 sed -i '/crucial code/d' Main.fs
 dotnet build
-assert_fails dotnet test --no-build
+run dotnet test --no-build
+assert_failure
 ```
 ~~~