2 files changed, 7 insertions, 11 deletions
diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go
index 0c49575511..9551c22d6e 100644
--- a/src/os/exec/exec.go
+++ b/src/os/exec/exec.go
@@ -748,12 +748,11 @@ func dedupEnvCase(caseInsensitive bool, env []string) []string {
 	out := make([]string, 0, len(env))
 	saw := make(map[string]int, len(env)) // key => index into out
 	for _, kv := range env {
-		eq := strings.Index(kv, "=")
-		if eq < 0 {
+		k, _, ok := strings.Cut(kv, "=")
+		if !ok {
 			out = append(out, kv)
 			continue
 		}
-		k := kv[:eq]
 		if caseInsensitive {
 			k = strings.ToLower(k)
 		}
@@ -775,11 +774,10 @@ func addCriticalEnv(env []string) []string {
 		return env
 	}
 	for _, kv := range env {
-		eq := strings.Index(kv, "=")
-		if eq < 0 {
+		k, _, ok := strings.Cut(kv, "=")
+		if !ok {
 			continue
 		}
-		k := kv[:eq]
 		if strings.EqualFold(k, "SYSTEMROOT") {
 			// We already have it.
 			return env
diff --git a/src/os/exec/exec_test.go b/src/os/exec/exec_test.go
index d854e0de84..459ba39dff 100644
--- a/src/os/exec/exec_test.go
+++ b/src/os/exec/exec_test.go
@@ -166,12 +166,10 @@ func TestCatGoodAndBadFile(t *testing.T) {
 	if _, ok := err.(*exec.ExitError); !ok {
 		t.Errorf("expected *exec.ExitError from cat combined; got %T: %v", err, err)
 	}
-	s := string(bs)
-	sp := strings.SplitN(s, "\n", 2)
-	if len(sp) != 2 {
-		t.Fatalf("expected two lines from cat; got %q", s)
+	errLine, body, ok := strings.Cut(string(bs), "\n")
+	if !ok {
+		t.Fatalf("expected two lines from cat; got %q", bs)
 	}
-	errLine, body := sp[0], sp[1]
 	if !strings.HasPrefix(errLine, "Error: open /bogus/file.foo") {
 		t.Errorf("expected stderr to complain about file; got %q", errLine)
 	}