diff --git a/generic/cursor.c b/generic/cursor.c
index 79ca634..8502102 100644
--- a/generic/cursor.c
+++ b/generic/cursor.c
@@ -334,16 +334,12 @@ mongotcl_cursorObjectObjCmd(ClientData cData, Tcl_Interp *interp, int objc, Tcl_
 		}
 
 		case OPT_CURSOR_BSON: {
-			char *bsonCommandObject;
-
 			if (objc != 3) {
 				Tcl_WrongNumArgs (interp, 2, objv, "bsonName");
 				return TCL_ERROR;
 			}
 
-			bsonCommandObject = Tcl_GetString (objv[2]);
-	
-			return mongotcl_cmdNameObjSetBson (interp, bsonCommandObject, mongo_cursor_bson (mc->cursor));
+			return mongotcl_cmdNameObjSetBson (interp, objv[2], mongo_cursor_bson (mc->cursor));
 		}
 
 		case OPT_CURSOR_NEXT: {
diff --git a/generic/mongotcl.c b/generic/mongotcl.c
index 656c453..b253a31 100644
--- a/generic/mongotcl.c
+++ b/generic/mongotcl.c
@@ -820,24 +820,26 @@ mongotcl_mongoObjectObjCmd(ClientData cData, Tcl_Interp *interp, int objc, Tcl_O
 
 		case OPT_IS_MASTER: {
 			bson *bsonResult;
+			int status = 0;
 
-			if (objc != 3) {
-				Tcl_WrongNumArgs (interp, 1, objv, "is_master bsonResult");
-				return TCL_ERROR;
-			}
-
-			if (mongotcl_cmdNameObjToBson (interp, objv[3], &bsonResult) == TCL_ERROR) {
-				Tcl_AddErrorInfo (interp, " while locating bson result object");
+			if (objc < 2 || objc > 3) {
+				Tcl_WrongNumArgs (interp, 1, objv, "is_master ?bsonResult?");
 				return TCL_ERROR;
 			}
 
-
-			if (mongo_cmd_ismaster (md->conn, bsonResult) == MONGO_OK) {
-				Tcl_SetObjResult (interp, Tcl_NewIntObj(1));
+			if (objc == 2) {
+				status = mongo_cmd_ismaster (md->conn, NULL);
 			} else {
-				Tcl_SetObjResult (interp, Tcl_NewIntObj(0));
+				if (mongotcl_cmdNameObjToBson (interp, objv[2], &bsonResult) == TCL_ERROR) {
+					Tcl_AddErrorInfo (interp, " while locating bson result object");
+					return TCL_ERROR;
+				}
+
+				status = mongo_cmd_ismaster (md->conn, bsonResult);
 			}
 
+			Tcl_SetObjResult (interp, Tcl_NewBooleanObj (status));
+
 			break;
 		}