diff --git a/Makefile b/Makefile
index 084a61b25..b558e7708 100644
--- a/Makefile
+++ b/Makefile
@@ -55,6 +55,7 @@ clean:
 
 fmt:
 	@go fmt . ./compiler ./ir ./src/examples/* ./src/machine ./src/runtime ./src/sync
+	@go fmt ./testdata/*.go
 
 gen-device: gen-device-nrf gen-device-avr