diff --git a/tests/.gitignore b/tests/.gitignore
new file mode 100644
index 000000000..e94ebb2fd
--- /dev/null
+++ b/tests/.gitignore
@@ -0,0 +1,4 @@
+# In the tests directory we want to allow including files matching *.out but
+# exclude temporary test result files.
+!*.out
+*.tmp.*