diff --git a/test/Dockerfile b/test/Dockerfile
index 9638acd..de236cd 100644
--- a/test/Dockerfile
+++ b/test/Dockerfile
@@ -43,6 +43,10 @@ COPY --chown=test:test conf.d      $TEST_HOME/.config/fish/conf.d/
 COPY --chown=test:test functions   $TEST_HOME/.config/fish/functions/
 RUN ls -R $TEST_HOME/.config/fish/
 
+# Signal we're safely running in a container;
+# we abort the tests to avoid breaking the host system!
+ENV RUNNING_IN_CONTAINER=yessir
+
 # Run tests
 COPY test ./
 ENTRYPOINT ["cucumber"]
diff --git a/test/features/support/hooks.rb b/test/features/support/hooks.rb
index d26980e..3997193 100644
--- a/test/features/support/hooks.rb
+++ b/test/features/support/hooks.rb
@@ -2,6 +2,10 @@ require_relative '../step_definitions/setup'
 require_relative '../step_definitions/corner_cases.rb'
 
 BeforeAll do
+  if ENV.fetch('RUNNING_IN_CONTAINER', false) != 'yessir'
+    Kernel.abort("We don't seem to be running in a container; aborting for safety!")
+  end
+
   run_bash_command('sdk update')
 end
 
@@ -12,7 +16,6 @@ After do |scenario|
   _restore_install
 end
 
-# Uninstall all SDKMAN! candidates
 AfterAll do
   Dir["#{ENV['HOME']}/.sdkman/candidates/*/*"].each do |candidate_dir|
     _uninstall_candidate_version(candidate_dir)