--- a/src/file.c
+++ b/src/file.c
@@ -45,6 +45,8 @@
 #include "prefs.h"
 #include "xml.h"
 
+char    gstr[MAXCHAR];
+
 /****** load_fitsfiles *******************************************************
 PROTO	catstruct **load_fitsfiles(char *name, int *ncat, int * outcat,
                                    filenum *filetype, int *headflag)
--- a/src/fits/fitscat.h
+++ b/src/fits/fitscat.h
@@ -333,6 +333,6 @@
 		warning(char *msg1, char *msg2);
 
 
-int		bswapflag;
+extern int		bswapflag;
 
 #endif
--- a/src/fits/fitscheck.c
+++ b/src/fits/fitscheck.c
@@ -38,6 +38,8 @@
 #include "fitscat_defs.h"
 #include "fitscat.h"
 
+int   bswapflag;
+
 #define	ENCODE_OFFSET	0x30
 unsigned int	exclude[13] = {0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40,
 				0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60};
--- 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/prefs.c
+++ b/src/prefs.c
@@ -50,6 +50,8 @@
 #include 	"prefs.h"
 #include	"preflist.h"
 
+prefstruct  prefs;
+
 /********************************* dumpprefs ********************************/
 /*
 Print the default preference parameters.
--- a/src/prefs.h
+++ b/src/prefs.h
@@ -84,7 +84,7 @@
   double	time_diff;		    /* Execution time */
   }	prefstruct;
 
-prefstruct	prefs;
+extern prefstruct	prefs;
 
 /*----------------------------- Internal constants --------------------------*/