diff --git a/misc/cgo/errors/badsym_test.go b/misc/cgo/errors/badsym_test.go
index fc687567bf..bc3ba2b489 100644
--- a/misc/cgo/errors/badsym_test.go
+++ b/misc/cgo/errors/badsym_test.go
@@ -201,6 +201,10 @@ func cCompilerCmd(t *testing.T) []string {
 	if !lastSpace {
 		cc = append(cc, s[start:])
 	}
+
+	// Force reallocation (and avoid aliasing bugs) for tests that append to cc.
+	cc = cc[:len(cc):len(cc)]
+
 	return cc
 }
 
diff --git a/misc/cgo/testcarchive/carchive_test.go b/misc/cgo/testcarchive/carchive_test.go
index a821396c77..d36b97b70e 100644
--- a/misc/cgo/testcarchive/carchive_test.go
+++ b/misc/cgo/testcarchive/carchive_test.go
@@ -11,7 +11,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/fs"
 	"log"
 	"os"
 	"os/exec"
@@ -141,6 +140,9 @@ func testMain(m *testing.M) int {
 	libgodir = filepath.Join(GOPATH, "pkg", libbase, "testcarchive")
 	cc = append(cc, "-I", libgodir)
 
+	// Force reallocation (and avoid aliasing bugs) for parallel tests that append to cc.
+	cc = cc[:len(cc):len(cc)]
+
 	if GOOS == "windows" {
 		exeSuffix = ".exe"
 	}
@@ -248,29 +250,6 @@ func testInstall(t *testing.T, exe, libgoa, libgoh string, buildcmd ...string) {
 
 var badLineRegexp = regexp.MustCompile(`(?m)^#line [0-9]+ "/.*$`)
 
-// checkIsExecutable verifies that exe exists and has execute permission.
-//
-// (https://golang.org/issue/49693 notes failures with "no such file or
-// directory", so we want to double-check that the executable actually exists
-// immediately after we build it in order to better understand that failure
-// mode.)
-func checkIsExecutable(t *testing.T, exe string) {
-	t.Helper()
-	fi, err := os.Stat(exe)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if runtime.GOOS == "windows" {
-		// os.File doesn't check the "execute" permission on Windows files
-		// and as a result doesn't set that bit in a file's permissions.
-		// Assume that if the file exists it is “executable enough”.
-		return
-	}
-	if fi.Mode()&0111 == 0 {
-		t.Fatalf("%s is not executable: %0o", exe, fi.Mode()&fs.ModePerm)
-	}
-}
-
 // checkLineComments checks that the export header generated by
 // -buildmode=c-archive doesn't have any absolute paths in the #line
 // comments. We don't want those paths because they are unhelpful for
@@ -964,7 +943,6 @@ func TestSIGPROF(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	checkIsExecutable(t, "./testp6"+exeSuffix)
 
 	argv := cmdToRun("./testp6")
 	cmd = exec.Command(argv[0], argv[1:]...)
@@ -1113,7 +1091,6 @@ func TestManyCalls(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	checkIsExecutable(t, "./testp7"+exeSuffix)
 
 	argv := cmdToRun("./testp7")
 	cmd = exec.Command(argv[0], argv[1:]...)
@@ -1170,7 +1147,6 @@ func TestPreemption(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	checkIsExecutable(t, "./testp8"+exeSuffix)
 
 	argv := cmdToRun("./testp8")
 	cmd = exec.Command(argv[0], argv[1:]...)
diff --git a/misc/cgo/testcshared/cshared_test.go b/misc/cgo/testcshared/cshared_test.go
index 13ec8761e8..c9e9e5fe63 100644
--- a/misc/cgo/testcshared/cshared_test.go
+++ b/misc/cgo/testcshared/cshared_test.go
@@ -117,6 +117,9 @@ func testMain(m *testing.M) int {
 	}
 	cc = append(cc, "-I", filepath.Join("pkg", libgodir))
 
+	// Force reallocation (and avoid aliasing bugs) for parallel tests that append to cc.
+	cc = cc[:len(cc):len(cc)]
+
 	if GOOS == "windows" {
 		exeSuffix = ".exe"
 	}