diff --git a/internal/api/client.go b/internal/api/client.go
index 9aa4986..b04ee54 100644
--- a/internal/api/client.go
+++ b/internal/api/client.go
@@ -369,10 +369,49 @@ type Event struct {
 }
 
 type EventShield struct {
-	Colour string // "Red" or "Grey"
-	Code   string // "VerificationViolation" or similar
+	Colour EventShieldColour
+	Code   EventShieldCode
 }
 
+type EventShieldColour string
+
+var (
+	EventShieldColourRed  EventShieldColour = "Red"
+	EventShieldColourGrey EventShieldColour = "Grey"
+)
+
+type EventShieldCode string
+
+var (
+	// "An unknown reason from the crypto library (if you see this, it is a bug in matrix-js-sdk)."
+	EventShieldCodeUnknown EventShieldCode = "Unknown"
+
+	// "Encrypted by an unverified user."
+	EventShieldCodeUnverifiedIdentity EventShieldCode = "UnverifiedIdentity"
+
+	// "Encrypted by a device not verified by its owner."
+	EventShieldCodeUnsignedDevice EventShieldCode = "UnsignedDevice"
+
+	// "Encrypted by an unknown or deleted device."
+	EventShieldCodeUnknownDevice EventShieldCode = "UnknownDevice"
+
+	// "The authenticity of this encrypted message can't be guaranteed on this device."
+	//
+	// i.e.: the key has been forwarded, or retrieved from an insecure backup.
+	EventShieldCodeAuthenticityNotGuaranteed EventShieldCode = "AuthenticityNotGuaranteed"
+
+	// "The (deprecated) sender_key field in the event does not match the Ed25519 key of the device that sent us the decryption keys.
+	//
+	// No longer used with rust crypto stack, since it doesn't check the sender_key field.
+	EventShieldCodeMismatchedSenderKey EventShieldCode = "MismatchedSenderKey"
+
+	// "The event was sent unencrypted in an encrypted room."
+	EventShieldCodeSentInClear EventShieldCode = "SentInClear"
+
+	// "The sender was previously verified but changed their identity."
+	EventShieldCodeVerificationViolation EventShieldCode = "VerificationViolation"
+)
+
 type Waiter interface {
 	// Wait for something to happen, up until the timeout s. If nothing happens,
 	// fail the test with the formatted string provided.
diff --git a/internal/api/js/js.go b/internal/api/js/js.go
index 2216d1a..5a9a288 100644
--- a/internal/api/js/js.go
+++ b/internal/api/js/js.go
@@ -587,58 +587,37 @@ func (c *JSClient) GetEventShield(t ct.TestLike, roomID, eventID string) (*api.E
 	var eventShield api.EventShield
 	switch encryptionInfo.ShieldColour {
 	case 1:
-		eventShield.Colour = "grey"
+		eventShield.Colour = api.EventShieldColourGrey
 	case 2:
-		eventShield.Colour = "red"
+		eventShield.Colour = api.EventShieldColourRed
 	default:
 		return nil, fmt.Errorf("unknown shield colour: %d", encryptionInfo.ShieldColour)
 	}
 
 	switch encryptionInfo.ShieldReason {
 	case 0:
-		/** An unknown reason from the crypto library (if you see this, it is a bug in matrix-js-sdk). */
-		eventShield.Code = "Unknown"
+		eventShield.Code = api.EventShieldCodeUnknown
 
 	case 1:
-		/** "Encrypted by an unverified user." */
-		eventShield.Code = "UnverifiedIdentity"
+		eventShield.Code = api.EventShieldCodeUnverifiedIdentity
 
 	case 2:
-		/** "Encrypted by a device not verified by its owner." */
-		eventShield.Code = "UnsignedDevice"
+		eventShield.Code = api.EventShieldCodeUnsignedDevice
 
 	case 3:
-		/** "Encrypted by an unknown or deleted device." */
-		eventShield.Code = "UnknownDevice"
+		eventShield.Code = api.EventShieldCodeUnknownDevice
 
 	case 4:
-		/**
-		 * "The authenticity of this encrypted message can't be guaranteed on this device."
-		 *
-		 * i.e.: the key has been forwarded, or retrieved from an insecure backup.
-		 */
-		eventShield.Code = "AuthenticityNotGuaranteed"
+		eventShield.Code = api.EventShieldCodeAuthenticityNotGuaranteed
 
 	case 5:
-		/**
-		 * The (deprecated) sender_key field in the event does not match the Ed25519 key of the device that sent us the
-		 * decryption keys.
-		 *
-		 * No longer used with rust crypto stack, since it doesn't check the sender_key field.
-		 */
-		eventShield.Code = "MismatchedSenderKey"
+		eventShield.Code = api.EventShieldCodeMismatchedSenderKey
 
 	case 6:
-		/**
-		 * The event was sent unencrypted in an encrypted room.
-		 */
-		eventShield.Code = "SentInClear"
+		eventShield.Code = api.EventShieldCodeSentInClear
 
 	case 7:
-		/**
-		 * The sender was previously verified but changed their identity.
-		 */
-		eventShield.Code = "VerificationViolation"
+		eventShield.Code = api.EventShieldCodeVerificationViolation
 
 	default:
 		return nil, fmt.Errorf("unknown shield reason code: %d", encryptionInfo.ShieldReason)
diff --git a/internal/api/rust/rust.go b/internal/api/rust/rust.go
index 7c17401..207f9d7 100644
--- a/internal/api/rust/rust.go
+++ b/internal/api/rust/rust.go
@@ -350,21 +350,21 @@ func (c *RustClient) GetEventShield(t ct.TestLike, roomID, eventID string) (*api
 	}
 	shieldState := timelineItem.LazyProvider.GetShields(false)
 
-	codeToString := func(code matrix_sdk_common.ShieldStateCode) string {
-		var result string
+	codeToString := func(code matrix_sdk_common.ShieldStateCode) api.EventShieldCode {
+		var result api.EventShieldCode
 		switch code {
 		case matrix_sdk_common.ShieldStateCodeAuthenticityNotGuaranteed:
-			result = "AuthenticityNotGuaranteed"
+			result = api.EventShieldCodeAuthenticityNotGuaranteed
 		case matrix_sdk_common.ShieldStateCodeUnknownDevice:
-			result = "UnknownDevice"
+			result = api.EventShieldCodeUnknownDevice
 		case matrix_sdk_common.ShieldStateCodeUnsignedDevice:
-			result = "UnsignedDevice"
+			result = api.EventShieldCodeUnsignedDevice
 		case matrix_sdk_common.ShieldStateCodeUnverifiedIdentity:
-			result = "UnverifiedIdentity"
+			result = api.EventShieldCodeUnverifiedIdentity
 		case matrix_sdk_common.ShieldStateCodeSentInClear:
-			result = "SentInClear"
+			result = api.EventShieldCodeSentInClear
 		case matrix_sdk_common.ShieldStateCodeVerificationViolation:
-			result = "VerificationViolation"
+			result = api.EventShieldCodeVerificationViolation
 		default:
 			log.Panicf("Unknown shield code %d", code)
 		}
@@ -381,13 +381,13 @@ func (c *RustClient) GetEventShield(t ct.TestLike, roomID, eventID string) (*api
 
 		case matrix_sdk_ffi.ShieldStateGrey:
 			eventShield = &api.EventShield{
-				Colour: "grey",
+				Colour: api.EventShieldColourGrey,
 				Code:   codeToString(shield.(matrix_sdk_ffi.ShieldStateGrey).Code),
 			}
 
 		case matrix_sdk_ffi.ShieldStateRed:
 			eventShield = &api.EventShield{
-				Colour: "red",
+				Colour: api.EventShieldColourRed,
 				Code:   codeToString(shield.(matrix_sdk_ffi.ShieldStateRed).Code),
 			}
 		}