diff --git a/helmexec/exec.go b/helmexec/exec.go
index 32159849..45d60295 100644
--- a/helmexec/exec.go
+++ b/helmexec/exec.go
@@ -77,7 +77,7 @@ func (helm *execer) DecryptSecret(name string) (string, error) {
 }
 
 func (helm *execer) DiffRelease(name, chart string, flags ...string) error {
-	out, err := helm.exec(append([]string{"diff", "upgrade", name, chart}, flags...)...)
+	out, err := helm.exec(append([]string{"diff", "upgrade", "--allow-unreleased", name, chart}, flags...)...)
 	helm.write(out)
 	return err
 }
diff --git a/helmexec/exec_test.go b/helmexec/exec_test.go
index bcb52415..caa7ee58 100644
--- a/helmexec/exec_test.go
+++ b/helmexec/exec_test.go
@@ -139,14 +139,14 @@ func Test_DiffRelease(t *testing.T) {
 	var buffer bytes.Buffer
 	helm := MockExecer(&buffer, "dev")
 	helm.DiffRelease("release", "chart", "--timeout 10", "--wait")
-	expected := "exec: helm diff upgrade release chart --timeout 10 --wait --kube-context dev\n"
+	expected := "exec: helm diff upgrade --allow-unreleased release chart --timeout 10 --wait --kube-context dev\n"
 	if buffer.String() != expected {
 		t.Errorf("helmexec.DiffRelease()\nactual = %v\nexpect = %v", buffer.String(), expected)
 	}
 
 	buffer.Reset()
 	helm.DiffRelease("release", "chart")
-	expected = "exec: helm diff upgrade release chart --kube-context dev\n"
+	expected = "exec: helm diff upgrade --allow-unreleased release chart --kube-context dev\n"
 	if buffer.String() != expected {
 		t.Errorf("helmexec.DiffRelease()\nactual = %v\nexpect = %v", buffer.String(), expected)
 	}