diff --git a/app/src/types/generated/firewall_pb.d.ts b/app/src/types/generated/firewall_pb.d.ts
index f2739fb0..176c6b61 100644
--- a/app/src/types/generated/firewall_pb.d.ts
+++ b/app/src/types/generated/firewall_pb.d.ts
@@ -193,6 +193,11 @@ export class Action extends jspb.Message {
   getSessionId_asB64(): string;
   setSessionId(value: Uint8Array | string): void;
 
+  getMacaroonIdentifier(): Uint8Array | string;
+  getMacaroonIdentifier_asU8(): Uint8Array;
+  getMacaroonIdentifier_asB64(): string;
+  setMacaroonIdentifier(value: Uint8Array | string): void;
+
   serializeBinary(): Uint8Array;
   toObject(includeInstance?: boolean): Action.AsObject;
   static toObject(includeInstance: boolean, msg: Action): Action.AsObject;
@@ -216,6 +221,7 @@ export namespace Action {
     state: ActionStateMap[keyof ActionStateMap],
     errorReason: string,
     sessionId: Uint8Array | string,
+    macaroonIdentifier: Uint8Array | string,
   }
 }
 
diff --git a/app/src/types/generated/firewall_pb.js b/app/src/types/generated/firewall_pb.js
index 4c970167..a1886d62 100644
--- a/app/src/types/generated/firewall_pb.js
+++ b/app/src/types/generated/firewall_pb.js
@@ -1303,7 +1303,8 @@ proto.litrpc.Action.toObject = function(includeInstance, msg) {
     timestamp: jspb.Message.getFieldWithDefault(msg, 8, "0"),
     state: jspb.Message.getFieldWithDefault(msg, 9, 0),
     errorReason: jspb.Message.getFieldWithDefault(msg, 10, ""),
-    sessionId: msg.getSessionId_asB64()
+    sessionId: msg.getSessionId_asB64(),
+    macaroonIdentifier: msg.getMacaroonIdentifier_asB64()
   };
 
   if (includeInstance) {
@@ -1384,6 +1385,10 @@ proto.litrpc.Action.deserializeBinaryFromReader = function(msg, reader) {
       var value = /** @type {!Uint8Array} */ (reader.readBytes());
       msg.setSessionId(value);
       break;
+    case 12:
+      var value = /** @type {!Uint8Array} */ (reader.readBytes());
+      msg.setMacaroonIdentifier(value);
+      break;
     default:
       reader.skipField();
       break;
@@ -1490,6 +1495,13 @@ proto.litrpc.Action.serializeBinaryToWriter = function(message, writer) {
       f
     );
   }
+  f = message.getMacaroonIdentifier_asU8();
+  if (f.length > 0) {
+    writer.writeBytes(
+      12,
+      f
+    );
+  }
 };
 
 
@@ -1715,6 +1727,48 @@ proto.litrpc.Action.prototype.setSessionId = function(value) {
 };
 
 
+/**
+ * optional bytes macaroon_identifier = 12;
+ * @return {!(string|Uint8Array)}
+ */
+proto.litrpc.Action.prototype.getMacaroonIdentifier = function() {
+  return /** @type {!(string|Uint8Array)} */ (jspb.Message.getFieldWithDefault(this, 12, ""));
+};
+
+
+/**
+ * optional bytes macaroon_identifier = 12;
+ * This is a type-conversion wrapper around `getMacaroonIdentifier()`
+ * @return {string}
+ */
+proto.litrpc.Action.prototype.getMacaroonIdentifier_asB64 = function() {
+  return /** @type {string} */ (jspb.Message.bytesAsB64(
+      this.getMacaroonIdentifier()));
+};
+
+
+/**
+ * optional bytes macaroon_identifier = 12;
+ * Note that Uint8Array is not supported on all browsers.
+ * @see http://caniuse.com/Uint8Array
+ * This is a type-conversion wrapper around `getMacaroonIdentifier()`
+ * @return {!Uint8Array}
+ */
+proto.litrpc.Action.prototype.getMacaroonIdentifier_asU8 = function() {
+  return /** @type {!Uint8Array} */ (jspb.Message.bytesAsU8(
+      this.getMacaroonIdentifier()));
+};
+
+
+/**
+ * @param {!(string|Uint8Array)} value
+ * @return {!proto.litrpc.Action} returns this
+ */
+proto.litrpc.Action.prototype.setMacaroonIdentifier = function(value) {
+  return jspb.Message.setProto3BytesField(this, 12, value);
+};
+
+
 /**
  * @enum {number}
  */
diff --git a/litrpc/firewall.pb.go b/litrpc/firewall.pb.go
index 23a991ee..b79c6c6a 100644
--- a/litrpc/firewall.pb.go
+++ b/litrpc/firewall.pb.go
@@ -464,6 +464,9 @@ type Action struct {
 	ErrorReason string `protobuf:"bytes,10,opt,name=error_reason,json=errorReason,proto3" json:"error_reason,omitempty"`
 	// The ID of the session under which the action was performed.
 	SessionId []byte `protobuf:"bytes,11,opt,name=session_id,json=sessionId,proto3" json:"session_id,omitempty"`
+	// The 4 byte identifier of the macaroon that was used to perform the action.
+	// This is derived from the last 4 bytes of the macaroon's root key ID.
+	MacaroonIdentifier []byte `protobuf:"bytes,12,opt,name=macaroon_identifier,json=macaroonIdentifier,proto3" json:"macaroon_identifier,omitempty"`
 }
 
 func (x *Action) Reset() {
@@ -575,6 +578,13 @@ func (x *Action) GetSessionId() []byte {
 	return nil
 }
 
+func (x *Action) GetMacaroonIdentifier() []byte {
+	if x != nil {
+		return x.MacaroonIdentifier
+	}
+	return nil
+}
+
 var File_firewall_proto protoreflect.FileDescriptor
 
 var file_firewall_proto_rawDesc = []byte{
@@ -629,7 +639,7 @@ var file_firewall_proto_rawDesc = []byte{
 	0x20, 0x01, 0x28, 0x04, 0x52, 0x0f, 0x6c, 0x61, 0x73, 0x74, 0x49, 0x6e, 0x64, 0x65, 0x78, 0x4f,
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 	0x6e, 0x12, 0x1d, 0x0a, 0x0a, 0x61, 0x63, 0x74, 0x6f, 0x72, 0x5f, 0x6e, 0x61, 0x6d, 0x65, 0x18,
 	0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x09, 0x61, 0x63, 0x74, 0x6f, 0x72, 0x4e, 0x61, 0x6d, 0x65,
 	0x12, 0x21, 0x0a, 0x0c, 0x66, 0x65, 0x61, 0x74, 0x75, 0x72, 0x65, 0x5f, 0x6e, 0x61, 0x6d, 0x65,
@@ -653,28 +663,31 @@ var file_firewall_proto_rawDesc = []byte{
 	0x72, 0x72, 0x6f, 0x72, 0x5f, 0x72, 0x65, 0x61, 0x73, 0x6f, 0x6e, 0x18, 0x0a, 0x20, 0x01, 0x28,
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 }
 
 var (
diff --git a/litrpc/firewall.proto b/litrpc/firewall.proto
index 1a4dff43..c6ff0061 100644
--- a/litrpc/firewall.proto
+++ b/litrpc/firewall.proto
@@ -209,6 +209,12 @@ message Action {
     The ID of the session under which the action was performed.
     */
     bytes session_id = 11;
+
+    /*
+    The 4 byte identifier of the macaroon that was used to perform the action.
+    This is derived from the last 4 bytes of the macaroon's root key ID.
+    */
+    bytes macaroon_identifier = 12;
 }
 
 enum ActionState {
diff --git a/litrpc/firewall.swagger.json b/litrpc/firewall.swagger.json
index d76caa9b..a62ea042 100644
--- a/litrpc/firewall.swagger.json
+++ b/litrpc/firewall.swagger.json
@@ -132,6 +132,11 @@
           "type": "string",
           "format": "byte",
           "description": "The ID of the session under which the action was performed."
+        },
+        "macaroon_identifier": {
+          "type": "string",
+          "format": "byte",
+          "description": "The 4 byte identifier of the macaroon that was used to perform the action.\nThis is derived from the last 4 bytes of the macaroon's root key ID."
         }
       }
     },
diff --git a/proto/firewall.proto b/proto/firewall.proto
index 9f429b78..a41749b2 100644
--- a/proto/firewall.proto
+++ b/proto/firewall.proto
@@ -209,6 +209,12 @@ message Action {
     The ID of the session under which the action was performed.
     */
     bytes session_id = 11;
+
+    /*
+    The 4 byte identifier of the macaroon that was used to perform the action.
+    This is derived from the last 4 bytes of the macaroon's root key ID.
+    */
+    bytes macaroon_identifier = 12;
 }
 
 enum ActionState {
diff --git a/session_rpcserver.go b/session_rpcserver.go
index 9fcf78a4..59ebfdb2 100644
--- a/session_rpcserver.go
+++ b/session_rpcserver.go
@@ -738,6 +738,7 @@ func (s *sessionRpcServer) ListActions(ctx context.Context,
 
 		resp[i] = &litrpc.Action{
 			SessionId:          sessionID[:],
+			MacaroonIdentifier: a.MacaroonIdentifier[:],
 			ActorName:          a.ActorName,
 			FeatureName:        a.FeatureName,
 			Trigger:            a.Trigger,