diff --git a/stages/terraform-module-promise/main.go b/stages/terraform-module-promise/main.go
index 6c48a0b..1b1f73c 100644
--- a/stages/terraform-module-promise/main.go
+++ b/stages/terraform-module-promise/main.go
@@ -15,8 +15,8 @@ func main() {
 	yamlFile := GetEnv("KRATIX_INPUT_FILE", "/kratix/input/object.yaml")
 	outputDir := GetEnv("KRATIX_OUTPUT_DIR", "/kratix/output")
 	moduleSource := MustHaveEnv("MODULE_SOURCE")
-	moduleVersion := MustHaveEnv("MODULE_VERSION")
-	modulePath := os.Getenv("MODULE_PATH") // optional
+	moduleVersion := os.Getenv("MODULE_VERSION") // optional as can be set with ?ref= in source
+	modulePath := os.Getenv("MODULE_PATH")       // optional
 
 	yamlContent, err := os.ReadFile(yamlFile)
 	if err != nil {
@@ -44,9 +44,14 @@ func main() {
 
 	uniqueFileName := strings.ToLower(fmt.Sprintf("%s_%s_%s", kind, namespace, name))
 
-	source := fmt.Sprintf("%s//%s?ref=%s", moduleSource, modulePath, moduleVersion)
+	version := ""
+	if moduleVersion != "" {
+		version = fmt.Sprintf("?ref=%s", moduleVersion)
+	}
+
+	source := fmt.Sprintf("%s//%s%s", moduleSource, modulePath, version)
 	if modulePath == "" {
-		source = fmt.Sprintf("%s?ref=%s", moduleSource, moduleVersion)
+		source = fmt.Sprintf("%s%s", moduleSource, version)
 	}
 
 	module := map[string]map[string]map[string]any{
diff --git a/stages/terraform-module-promise/test/stage_test.go b/stages/terraform-module-promise/test/stage_test.go
index 1dcfc28..0060626 100644
--- a/stages/terraform-module-promise/test/stage_test.go
+++ b/stages/terraform-module-promise/test/stage_test.go
@@ -105,3 +105,36 @@ var _ = Describe("From TF module to Promise Stage", func() {
 		Expect(string(output)).To(MatchJSON(expectedOutputNoSpec))
 	})
 })
+
+var _ = Describe("Different variable inputs", func() {
+	var (
+		envVars map[string]string
+		tmpDir  string
+	)
+
+	BeforeEach(func() {
+		var err error
+		tmpDir, err = os.MkdirTemp("", "kratix")
+		Expect(err).NotTo(HaveOccurred())
+	})
+
+	AfterEach(func() {
+		os.RemoveAll(tmpDir)
+	})
+
+	It("No version provided", func() {
+		envVars = map[string]string{
+			"KRATIX_INPUT_FILE": "assets/test-object.yaml",
+			"KRATIX_OUTPUT_DIR": tmpDir,
+			"MODULE_SOURCE":     "git::example.com?ref=1.0.0",
+		}
+
+		session := runWithEnv(envVars)
+		Eventually(session).Should(gexec.Exit())
+		Expect(session.Buffer()).To(gbytes.Say("Terraform JSON configuration written to %s/testobject_non-default_test-object.tf.json", tmpDir))
+		Expect(session).To(gexec.Exit(0))
+		output, err := os.ReadFile(filepath.Join(tmpDir, "testobject_non-default_test-object.tf.json"))
+		Expect(err).NotTo(HaveOccurred())
+		Expect(string(output)).To(MatchJSON(expectedOutput))
+	})
+})