diff --git a/src/test/run-make/target-specs/Makefile b/src/test/run-make/target-specs/Makefile
index 0c9a0169c1ab..6b58ad7b6dff 100644
--- a/src/test/run-make/target-specs/Makefile
+++ b/src/test/run-make/target-specs/Makefile
@@ -6,3 +6,4 @@ all:
 	$(RUSTC) foo.rs --target=my-incomplete-platform.json 2>&1 | grep 'Field llvm-target'
 	RUST_TARGET_PATH=. $(RUSTC) foo.rs --target=my-awesome-platform --crate-type=lib --emit=asm
 	RUST_TARGET_PATH=. $(RUSTC) foo.rs --target=x86_64-unknown-linux-gnu --crate-type=lib --emit=asm
+	$(RUSTC) -Z unstable-options --target=my-awesome-platform.json --print target-spec-json > $(TMPDIR)/test-platform.json && $(RUSTC) -Z unstable-options --target=$(TMPDIR)/test-platform.json --print target-spec-json | diff -q $(TMPDIR)/test-platform.json -