diff --git a/WIN32-Code/getopt.h b/WIN32-Code/getopt.h
index 7137f037..796f4550 100644
--- a/WIN32-Code/getopt.h
+++ b/WIN32-Code/getopt.h
@@ -23,8 +23,8 @@ struct option
 #define required_argument 1
 #define optional_argument 2
 
-int getopt(int, char**, char*);
-int getopt_long(int, char**, char*, struct option*, int*);
+int getopt(int, char**, const char*);
+int getopt_long(int, char**, const char*, const struct option*, int*);
 
 #ifdef __cplusplus
 }
diff --git a/WIN32-Code/getopt_long.c b/WIN32-Code/getopt_long.c
index 8bbc2053..03f0c01a 100644
--- a/WIN32-Code/getopt_long.c
+++ b/WIN32-Code/getopt_long.c
@@ -160,8 +160,8 @@ int
 getopt_long(nargc, nargv, options, long_options, index)
 	int nargc;
 	char ** nargv;
-	char * options;
-	struct option * long_options;
+	const char * options;
+	const struct option * long_options;
 	int * index;
 {
 	int retval;