diff --git a/commercelayer/resource_payment_method.go b/commercelayer/resource_payment_method.go
index e1183b5..57c259d 100644
--- a/commercelayer/resource_payment_method.go
+++ b/commercelayer/resource_payment_method.go
@@ -39,11 +39,12 @@ func resourcePaymentMethod() *schema.Resource {
 				Elem: &schema.Resource{
 					Schema: map[string]*schema.Schema{
 						"payment_source_type": {
-							Description: "The payment source type, can be one of: 'AdyenPayment', 'BraintreePayment', " +
-								"'CheckoutComPayment', 'CreditCard', 'ExternalPayment', 'KlarnaPayment', 'PaypalPayment', " +
-								"'StripePayment', or 'WireTransfer'.",
-							Type:     schema.TypeString,
-							Required: true,
+							Description: "The payment source type, can be one of: AdyenPayment, BraintreePayment, " +
+								"CheckoutComPayment, CreditCard, ExternalPayment, KlarnaPayment, PaypalPayment, " +
+								"StripePayment or WireTransfer",
+							Type:             schema.TypeString,
+							Required:         true,
+							ValidateDiagFunc: paymentSourceValidation,
 						},
 						"currency_code": {
 							Description: "The international 3-letter currency code as defined by the ISO 4217 standard. " +
diff --git a/commercelayer/validation.go b/commercelayer/validation.go
index 066e5be..e03a5d0 100644
--- a/commercelayer/validation.go
+++ b/commercelayer/validation.go
@@ -30,3 +30,27 @@ var inventoryModelStrategyValidation = func(i interface{}, path cty.Path) diag.D
 	return diag.Errorf("Invalid inventory model strategy provided: %s. Must be one of %s",
 		i.(string), strings.Join(getInventoryModelStrategies(), ", "))
 }
+
+func getPaymentSources() []string {
+	return []string{
+		"AdyenPayment",
+		"BraintreePayment",
+		"CheckoutComPayment",
+		"CreditCard",
+		"ExternalPayment",
+		"KlarnaPayment",
+		"PaypalPayment",
+		"StripePayment",
+		"WireTransfer",
+	}
+}
+
+var paymentSourceValidation = func(i interface{}, path cty.Path) diag.Diagnostics {
+	for _, s := range getPaymentSources() {
+		if s == i.(string) {
+			return nil
+		}
+	}
+	return diag.Errorf("Invalid payment source provided: %s. Must be one of %s",
+		i.(string), strings.Join(getPaymentSources(), ", "))
+}
diff --git a/commercelayer/validation_test.go b/commercelayer/validation_test.go
index 0e2de41..263155d 100644
--- a/commercelayer/validation_test.go
+++ b/commercelayer/validation_test.go
@@ -14,3 +14,13 @@ func TestCurrencyCodeValidationOK(t *testing.T) {
 	diag := currencyCodeValidation("EUR", nil)
 	assert.False(t, diag.HasError())
 }
+
+func TestPaymentSourceValidationError(t *testing.T) {
+	diag := paymentSourceValidation("Adyen", nil)
+	assert.True(t, diag.HasError())
+}
+
+func TestPaymentSourceValidationOK(t *testing.T) {
+	diag := paymentSourceValidation("BraintreePayment", nil)
+	assert.False(t, diag.HasError())
+}