diff --git a/ChangeLog b/ChangeLog
index aad46dc84..140b1ce2c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2010-08-07  Robert Larice
+ * src/frontend/parse-bison.c ,
+ * src/frontend/parse-bison.h ,
+ * src/frontend/parse-bison.y :
+    bug fix,
+      avoid segfault, caused when parsing an unknown function in parse-bison.y
+
 2010-08-07 Dietmar Warning
  spicelib/devices/*/b4soimask.c, csw*.c, mos6load.c, soi3load.c, swnoise.c: 
     fix some wrong 'double' to 'int' assignments
diff --git a/src/frontend/parse-bison.c b/src/frontend/parse-bison.c
index b6216a6c1..8bf1edc50 100644
--- a/src/frontend/parse-bison.c
+++ b/src/frontend/parse-bison.c
@@ -161,7 +161,7 @@ typedef union YYSTYPE
   const char  *str;
   struct pnode *pnode;
 }
-/* Line 193 of yacc.c.  */
+/* Line 187 of yacc.c.  */
 #line 166 "parse-bison.c"
 	YYSTYPE;
 # define yystype YYSTYPE /* obsolescent; will be withdrawn */
@@ -1579,7 +1579,7 @@ yyreduce:
 
   case 19:
 #line 142 "parse-bison.y"
-    { (yyval.pnode) = mkfnode((yyvsp[(1) - (4)].str), (yyvsp[(3) - (4)].pnode)); ;}
+    { (yyval.pnode) = mkfnode((yyvsp[(1) - (4)].str), (yyvsp[(3) - (4)].pnode)); if(!(yyval.pnode)) YYABORT; ;}
     break;
 
   case 20:
diff --git a/src/frontend/parse-bison.h b/src/frontend/parse-bison.h
index 2e960387e..1657dc415 100644
--- a/src/frontend/parse-bison.h
+++ b/src/frontend/parse-bison.h
@@ -70,7 +70,7 @@ typedef union YYSTYPE
   const char  *str;
   struct pnode *pnode;
 }
-/* Line 1529 of yacc.c.  */
+/* Line 1489 of yacc.c.  */
 #line 75 "parse-bison.h"
 	YYSTYPE;
 # define yystype YYSTYPE /* obsolescent; will be withdrawn */
diff --git a/src/frontend/parse-bison.y b/src/frontend/parse-bison.y
index e2b1453c6..070aef64a 100644
--- a/src/frontend/parse-bison.y
+++ b/src/frontend/parse-bison.y
@@ -139,7 +139,7 @@ exp:
   | '-' exp  %prec NEG                { $$ = mkunode(UMINUS, $2); }
   | '~' exp                           { $$ = mkunode(NOT, $2); }
 
-  | TOK_STR '(' exp ')'               { $$ = mkfnode($1, $3); }
+  | TOK_STR '(' exp ')'               { $$ = mkfnode($1, $3); if(!$$) YYABORT; }
 
   | exp '=' exp                       { $$ = mkbnode(EQ, $1, $3); }
   | exp TOK_NE exp                    { $$ = mkbnode(NE, $1, $3); }