diff --git a/src/calculation/expression_parser.c b/src/calculation/expression_parser.c
index aefeb499ee..ac2cda000c 100644
--- a/src/calculation/expression_parser.c
+++ b/src/calculation/expression_parser.c
@@ -389,7 +389,7 @@ typedef struct parser_env {
 
     unsigned char  Token;
     unsigned char  asn_op;
-    unsigned       error_code;
+    ParseError     error_code;
 
     void          *numeric_value;
     void         *(*trans_numeric)(unsigned char  *digit_str,
@@ -477,7 +477,7 @@ void  exit_parser(parser_env_ptr pe)
 } /* exit_parser */
 
 /* return parser error code */
-unsigned get_parse_error(parser_env_ptr pe)
+ParseError get_parse_error(parser_env_ptr pe)
 {
   if (pe == NULL)
     return PARSER_NO_ERROR;
diff --git a/src/calculation/fin_spl_protos.h b/src/calculation/fin_spl_protos.h
index ccf84ad1e2..f178b54344 100644
--- a/src/calculation/fin_spl_protos.h
+++ b/src/calculation/fin_spl_protos.h
@@ -1,7 +1,29 @@
+/***************************************************************************
+ *              -------------------
+ *    create   : Tue Jul 11 20:21:18 2000
+ *    copyright: (C) 2000 by Terry D. Boldt
+ *    email    : tboldt@attglobal.net
+ *              -------------------
+ ***************************************************************************/
+/***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+/***************************************************************************
+ *  Global Function Prototypes
+ *  Tue Jul 11 20:21:18 2000
+ *
+ ***************************************************************************/
+
+#ifndef __FIN_SPL_PROTOS_H__
+#define __FIN_SPL_PROTOS_H__
 
 /*==================================================*/
-/* expression_parser.c
- */
+/* expression_parser.c */
 /* Line Number:  344 */
 parser_env_ptr init_parser(
                            var_store_ptr  predefined_vars,
@@ -16,3 +38,5 @@ parser_env_ptr init_parser(
                                                       void          *right_value),
                            void          *negate_numeric(void *value),
                            void           free_numeric(void *numeric_value));
+
+#endif
diff --git a/src/calculation/finproto.h b/src/calculation/finproto.h
index 6e7df02ed5..2e90cab747 100644
--- a/src/calculation/finproto.h
+++ b/src/calculation/finproto.h
@@ -19,6 +19,12 @@
  *
  ***************************************************************************/
 
+#ifndef __FINPROTO_H__
+#define __FINPROTO_H__
+
+#include <stdio.h>
+
+#include "finvar.h"
 
 /*==================================================*/
 /* fin.c
@@ -112,7 +118,7 @@ void                     Amortization_free(
 /* Line Number: 377 */
 void                     exit_parser(parser_env_ptr pe);
 /* Line Number: 400 */
-unsigned                 get_parse_error(parser_env_ptr pe);
+ParseError               get_parse_error(parser_env_ptr pe);
 /* Line Number: 408 */
 var_store_ptr            get_vars(parser_env_ptr pe);
 /* Line Number: 417 */
@@ -159,3 +165,5 @@ amort_sched_ptr          amort_opt(
 void                     prt_amortization_schedule(
                                                    amort_sched_ptr amortsched, /* amortization schedule to print */
                                                    FILE *ofile); /* output file */
+
+#endif
diff --git a/src/calculation/finvar.h b/src/calculation/finvar.h
index c009ea5aca..022d63d1a1 100644
--- a/src/calculation/finvar.h
+++ b/src/calculation/finvar.h
@@ -19,6 +19,9 @@
  *
  ***************************************************************************/
 
+#ifndef __FINVAR_H__
+#define __FINVAR_H__
+
 #if !defined( EOS )
 #define EOS '\x000'
 #endif
@@ -34,12 +37,16 @@
 #define INT_TYPE    '\x001'
 #define DBL_TYPE    '\x002'
 
-#define PARSER_NO_ERROR     0
-#define UNBALANCED_PARENS   1
-#define STACK_OVERFLOW      2
-#define STACK_UNDERFLOW     3
-#define UNDEFINED_CHARACTER 4
-#define NOT_A_VARIABLE      5
+typedef enum
+{
+  PARSER_NO_ERROR = 0,
+  UNBALANCED_PARENS,
+  STACK_OVERFLOW,
+  STACK_UNDERFLOW,
+  UNDEFINED_CHARACTER,
+  NOT_A_VARIABLE,
+  PARSER_NUM_ERRORS
+} ParseError;
 
 #define UNUSED_VAR  '\x000'
 #define USED_VAR    '\x001'
@@ -51,16 +58,15 @@
 #define MUL_OP  '*'
 #define ASN_OP  '='
 
-/* The following structure is used by the expression parser to store named and temporary
- * variables.
- */
+/* The following structure is used by the expression parser to store
+ * named and temporary variables.  */
 
 /* structure used for storing variables - used by expression parser/evaluator
  */
 typedef struct var_store *var_store_ptr;
 
 typedef struct var_store {
-    unsigned char *variable_name;   /* vairable name if variable, NULL otherwise        */
+    unsigned char *variable_name;   /* variable name if variable, NULL otherwise        */
     unsigned char  use_flag;        /* flag if variable has been assigned to            */
     unsigned char  assign_flag;     /* flag if variable is used                         */
     void          *value;           /* pointer to imp[lementation defined numeric value */
@@ -75,7 +81,7 @@ typedef struct var_store {
  * evaluate arithmetic operators '+', '-', '/', '*' */
 typedef struct numeric *numeric_ptr;
 typedef struct numeric {
-    unsigned char  type;            /* designates type of value                  */
+    unsigned char  type;            /* designates type of value */
     union {
         long int  int_value;        /* long integer value   */
         double    dbl_value;        /* double value         */
@@ -215,3 +221,5 @@ typedef struct financial_info {
 } financial_info;
 
 typedef struct parser_env *parser_env_ptr;
+
+#endif