diff --git a/test/main.lua b/test/main.lua
index 83a35d165..2e8b52df1 100644
--- a/test/main.lua
+++ b/test/main.lua
@@ -206,6 +206,7 @@ function save_test_status(status)
 end
 
 function finish_tests()
+    dfhack.internal.IN_TEST = false
     if done_command then
         dfhack.run_command(done_command)
     end
@@ -220,7 +221,9 @@ function load_tests(file, tests)
         dfhack.printerr('Failed to load file: ' .. tostring(err))
         return false
     else
+        dfhack.internal.IN_TEST = true
         local ok, err = pcall(code)
+        dfhack.internal.IN_TEST = false
         if not ok then
             dfhack.printerr('Error when running file: ' .. tostring(err))
             return false
@@ -260,7 +263,9 @@ function run_test(test, status, counts)
     test.private.checks = 0
     test.private.checks_ok = 0
     counts.tests = counts.tests + 1
+    dfhack.internal.IN_TEST = true
     local ok, err = pcall(test.func)
+    dfhack.internal.IN_TEST = false
     local passed = false
     if not ok then
         dfhack.printerr('test errored: ' .. test.name .. ': ' .. tostring(err))
diff --git a/test/test.lua b/test/test.lua
new file mode 100644
index 000000000..11f038d66
--- /dev/null
+++ b/test/test.lua
@@ -0,0 +1,3 @@
+function test.internal_in_test()
+    expect.true_(dfhack.internal.IN_TEST)
+end