diff --git a/pandatool/src/xfile/xLexer.cxx.prebuilt b/pandatool/src/xfile/xLexer.cxx.prebuilt
index 972d875560..77122a4782 100644
--- a/pandatool/src/xfile/xLexer.cxx.prebuilt
+++ b/pandatool/src/xfile/xLexer.cxx.prebuilt
@@ -302,44 +302,47 @@ static void yy_fatal_error YY_PROTO(( yyconst char msg[] ));
 	*yy_cp = '\0'; \
 	yy_c_buf_p = yy_cp;
 
-#define YY_NUM_RULES 33
-#define YY_END_OF_BUFFER 34
-static yyconst short int yy_acclist[146] =
+#define YY_NUM_RULES 34
+#define YY_END_OF_BUFFER 35
+static yyconst short int yy_acclist[172] =
     {   0,
-       34,   33,    2,   33,    1,   33,   30,   33,    4,   33,
-       33,   10,   33,   32,   33,    9,   33,   33,   26,   33,
-       11,   33,   31,   33,    7,   33,    8,   33,   32,   33,
-       32,   33,   32,   33,   32,   33,   32,   33,   32,   33,
-       32,   33,   32,   33,   32,   33,   32,   33,    5,   33,
-        6,   33,    1,    4,   26,   32,   26,   32,    3,   27,
-    16412,   32,   32,   32,   32,   32,   32,   32,   32,   32,
-       32,   32,   32,   32,   32,   29,    3,   27,   32,   32,
+       35,   33,   34,    2,   33,   34,    1,   34,   30,   33,
+       34,    4,   33,   34,   33,   34,   10,   33,   34,   32,
+       33,   34,    9,   33,   34,   33,   34,   26,   33,   34,
+       11,   33,   34,   31,   33,   34,    7,   33,   34,    8,
+       33,   34,   32,   33,   34,   32,   33,   34,   32,   33,
+       34,   32,   33,   34,   32,   33,   34,   32,   33,   34,
+       32,   33,   34,   32,   33,   34,   32,   33,   34,   32,
+       33,   34,    5,   33,   34,    6,   33,   34,    1,    4,
+       26,   32,   26,   32,    3,   27,16412,   32,   32,   32,
        32,   32,   32,   32,   32,   32,   32,   32,   32,   32,
-       32,   32, 8220,   32,   13,   32,   14,   32,   32,   32,
 
-       32,   32,   32,   32,   32,   32,   32,   32,   25,   32,
-       29,   29,   12,   32,   32,   32,   17,   32,   19,   32,
-       32,   32,   24,   32,   32,   22,   32,   32,   32,   16,
-       32,   18,   32,   20,   32,   32,   32,   29,   15,   32,
-       32,   23,   32,   21,   32
+       32,   29,    3,   27,   32,   32,   32,   32,   32,   32,
+       32,   32,   32,   32,   32,   32,   32,   32, 8220,   32,
+       13,   32,   14,   32,   32,   32,   32,   32,   32,   32,
+       32,   32,   32,   32,   25,   32,   29,   29,   12,   32,
+       32,   32,   17,   32,   19,   32,   32,   32,   24,   32,
+       32,   22,   32,   32,   32,   16,   32,   18,   32,   20,
+       32,   32,   32,   29,   15,   32,   32,   23,   32,   21,
+       32
     } ;
 
 static yyconst short int yy_accept[122] =
     {   0,
-        1,    1,    1,    2,    3,    5,    7,    9,   11,   12,
-       14,   16,   18,   19,   21,   23,   25,   27,   29,   31,
-       33,   35,   37,   39,   41,   43,   45,   47,   49,   51,
-       53,   54,   55,   55,   56,   57,   59,   59,   60,   62,
-       62,   63,   64,   65,   66,   67,   68,   69,   70,   71,
-       72,   73,   74,   75,   76,   77,   77,   78,   78,   79,
-       80,   81,   82,   83,   84,   85,   86,   87,   88,   89,
-       90,   91,   92,   93,   93,   93,   93,   93,   93,   94,
-       95,   97,   99,  100,  101,  102,  103,  104,  105,  106,
-      107,  108,  109,  111,  112,  113,  115,  116,  117,  119,
+        1,    1,    1,    2,    4,    7,    9,   12,   15,   17,
+       20,   23,   26,   28,   31,   34,   37,   40,   43,   46,
+       49,   52,   55,   58,   61,   64,   67,   70,   73,   76,
+       79,   80,   81,   81,   82,   83,   85,   85,   86,   88,
+       88,   89,   90,   91,   92,   93,   94,   95,   96,   97,
+       98,   99,  100,  101,  102,  103,  103,  104,  104,  105,
+      106,  107,  108,  109,  110,  111,  112,  113,  114,  115,
+      116,  117,  118,  119,  119,  119,  119,  119,  119,  120,
+      121,  123,  125,  126,  127,  128,  129,  130,  131,  132,
+      133,  134,  135,  137,  138,  139,  141,  142,  143,  145,
 
-      121,  122,  123,  125,  126,  128,  129,  129,  130,  132,
-      134,  136,  137,  138,  138,  139,  141,  142,  144,  146,
-      146
+      147,  148,  149,  151,  152,  154,  155,  155,  156,  158,
+      160,  162,  163,  164,  164,  165,  167,  168,  170,  172,
+      172
     } ;
 
 static yyconst int yy_ec[256] =
@@ -916,7 +919,7 @@ inline void accept() {
   x_col_number += yyleng;
 }
 
-#line 921 "lex.yy.c"
+#line 924 "lex.yy.c"
 
 /* Macros after this point can all be overridden by user definitions in
  * section 1.
@@ -1073,7 +1076,7 @@ YY_DECL
 
 
 
-#line 1078 "lex.yy.c"
+#line 1081 "lex.yy.c"
 
 	if ( yy_init )
 		{
@@ -1471,9 +1474,18 @@ YY_RULE_SETUP
 case 33:
 YY_RULE_SETUP
 #line 607 "xLexer.lxx"
+{
+  // Any other character is invalid.
+  accept();
+  xyyerror("Invalid character '" + string(xyytext) + "'.");
+}
+	YY_BREAK
+case 34:
+YY_RULE_SETUP
+#line 612 "xLexer.lxx"
 ECHO;
 	YY_BREAK
-#line 1478 "lex.yy.c"
+#line 1490 "lex.yy.c"
 			case YY_STATE_EOF(INITIAL):
 				yyterminate();
 
@@ -2348,4 +2360,4 @@ int main()
 	return 0;
 	}
 #endif
-#line 607 "xLexer.lxx"
+#line 612 "xLexer.lxx"