--- a/src/field.c
+++ b/src/field.c
@@ -42,6 +42,9 @@
 #include	"prefs.h"
 #include	"readimage.h"
 
+extern prefstruct prefs;
+char gstr[MAXCHAR];
+
 /********************************* newfield **********************************/
 /*
 Returns a pointer to a new field, ready to go!
--- a/src/fits/fitsbody.c
+++ b/src/fits/fitsbody.c
@@ -43,6 +43,7 @@
 #include	"fitscat_defs.h"
 #include	"fitscat.h"
 
+extern int bswapflag;
 size_t	body_maxram = BODY_DEFRAM,
 	body_maxvram = BODY_DEFVRAM,
 	body_ramleft, body_vramleft, body_ramflag;
--- a/src/fits/fitscat.h
+++ b/src/fits/fitscat.h
@@ -333,6 +333,6 @@ extern  void	error(int, char *, char *),
 		warning(char *msg1, char *msg2);
 
 
-int		bswapflag;
+extern int		bswapflag;
 
 #endif
--- a/src/fits/fitscheck.c
+++ b/src/fits/fitscheck.c
@@ -42,6 +42,7 @@
 unsigned int	exclude[13] = {0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40,
 				0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60};
 
+extern int bswapflag;
 /****** encode_checksum *****************************************************
 PROTO	void encode_checksum(unsigned int sum, char *str)
 PURPOSE	Encode a checksum to ASCII
--- a/src/fits/fitskey.c
+++ b/src/fits/fitskey.c
@@ -38,6 +38,7 @@
 #include	"fitscat_defs.h"
 #include	"fitscat.h"
 
+int bswapflag;
 /****** add_key ****************************************************************
 PROTO	int add_key(keystruct *key, tabstruct *tab, int pos)
 PURPOSE	Copy a key from one table to another.
--- a/src/fits/fitsread.c
+++ b/src/fits/fitsread.c
@@ -38,6 +38,7 @@
 #include	"fitscat_defs.h"
 #include	"fitscat.h"
 
+extern int bswapflag;
 char	padbuf[FBSIZE];
 
 /****** read_cat ***************************************************************
--- a/src/fits/fitswrite.c
+++ b/src/fits/fitswrite.c
@@ -39,6 +39,7 @@
 #include	"fitscat_defs.h"
 #include	"fitscat.h"
 
+extern int bswapflag;
 
 /****** save_cat **************************************************************
 PROTO	void save_cat(catstruct *cat, char *filename)
--- a/src/globals.h
+++ b/src/globals.h
@@ -30,7 +30,7 @@
 #include "types.h"
 
 /*----------------------- miscellaneous variables ---------------------------*/
-char		gstr[MAXCHAR];
+extern char		gstr[MAXCHAR];
 
 /*------------------------------- functions ---------------------------------*/
 extern	void	makeit(void),
--- a/src/main.c
+++ b/src/main.c
@@ -51,6 +51,8 @@ EXECUTABLE " [-c <configuration_file>] [-<keyword> <value>]\n"\
 extern const char	notokstr[];
 time_t		thetime, thetime2;
 
+extern prefstruct prefs;
+
 /********************************** main ************************************/
 int	main(int argc, char *argv[])
 
--- a/src/makeit.c
+++ b/src/makeit.c
@@ -45,6 +45,8 @@
 #include "readimage.h"
 #include "xml.h"
 
+extern prefstruct prefs;
+
 /********************************** makeit ***********************************/
 void	makeit(void)
   {
--- a/src/prefs.c
+++ b/src/prefs.c
@@ -51,6 +51,9 @@
 #include 	"prefs.h"
 #include	"preflist.h"
 
+extern int bswapflag;
+prefstruct prefs;
+
 /********************************* dumpprefs ********************************/
 /*
 Print the default preference parameters.
--- a/src/prefs.h
+++ b/src/prefs.h
@@ -86,7 +86,7 @@ typedef struct
   double	time_diff;			/* Execution time */
   }	prefstruct;
 
-  prefstruct	prefs;
+extern prefstruct prefs;
 
 
 /*-------------------------------- protos -----------------------------------*/
--- a/src/readimage.c
+++ b/src/readimage.c
@@ -39,6 +39,7 @@
 #include	"fits/fitscat.h"
 #include	"readimage.h"
 
+extern int bswapflag;
 /******************************** readdata **********************************/
 /*
 read and convert input data stream in PIXTYPE (float) format.
--- a/src/vector.c
+++ b/src/vector.c
@@ -46,6 +46,9 @@
 
 static void	chsort(crosstruct *ra, int n);
 
+extern char gstr[MAXCHAR];
+extern prefstruct prefs;
+
 /********************************** newvec **********************************/
 /*
 Returns a pointer to a new polygon, and initialize local context buffer:
--- a/src/xml.c
+++ b/src/xml.c
@@ -45,6 +45,7 @@
 #include "field.h"
 #include "xml.h"
 
+extern  prefstruct prefs;
 extern time_t		thetime,thetime2;	/* from makeit.c */
 extern pkeystruct	key[];			/* from preflist.h */
 extern char		keylist[][32];		/* from preflist.h */