diff --git a/main_test.go b/main_test.go
index 12afe9a6..5031c6aa 100644
--- a/main_test.go
+++ b/main_test.go
@@ -58,19 +58,9 @@ func runTest(path, tmpdir string, target string, t *testing.T) {
 		t.Fatal("could not read expected output file:", err)
 	}
 
-	var gc string
-	if target == "qemu" {
-		// make sure testdata/gc.go passes
-		gc = "marksweep"
-	} else {
-		// pick the default heap implementation
-		gc = ""
-	}
-
 	// Build the test binary.
 	config := &BuildConfig{
 		opt:        "z",
-		gc:         gc,
 		printIR:    false,
 		dumpSSA:    false,
 		debug:      false,
diff --git a/targets/cortex-m.json b/targets/cortex-m.json
index b373ef9b..c24c083f 100644
--- a/targets/cortex-m.json
+++ b/targets/cortex-m.json
@@ -1,6 +1,7 @@
 {
 	"build-tags": ["tinygo.arm", "js", "wasm"],
 	"compiler": "clang-7",
+	"gc": "marksweep",
 	"linker": "arm-none-eabi-ld",
 	"rtlib": "compiler-rt",
 	"cflags": [