diff --git a/add_trace_to_tabc.pl b/add_trace_to_tabc.pl
index 04be787..3186075 100644
--- a/add_trace_to_tabc.pl
+++ b/add_trace_to_tabc.pl
@@ -15,11 +15,11 @@
 # COPYRIGHT
 
 print <<EOF;
-extern elide_trace_reduce(int, int);
-extern elide_trace_shift(int,int);
-extern report_trace_shift(int);
-extern report_trace_reduce(int, int);
-extern report_trace_error(short *yyss, short *yyssp);
+extern void elide_trace_reduce(int, int);
+extern void elide_trace_shift(int,int);
+extern void report_trace_shift(int);
+extern void report_trace_reduce(int, int);
+extern void report_trace_error(short *yyss, short *yyssp);
 EOF
 
 while (<>) {
diff --git a/dfasyn/n2d.h b/dfasyn/n2d.h
index b2159ba..6c56abb 100644
--- a/dfasyn/n2d.h
+++ b/dfasyn/n2d.h
@@ -181,6 +181,10 @@ Expr * new_xor_expr(Expr *c1, Expr *c2);
 Expr * new_cond_expr(Expr *c1, Expr *c2, Expr *c3);
 Expr * new_sym_expr(char *sym_name);
 
+int yyparse(void);
+void yyerror(char *);
+int yylex(void);
+
 void define_symbol(Evaluator *x, char *name, Expr *e);
 void define_result(Evaluator *x, char *string, Expr *e, int early);
 void define_symresult(Evaluator *x, char *string, Expr *e, int early);