diff -up chemtool-1.6.14/ct1.h.gcc10 chemtool-1.6.14/ct1.h

--- chemtool-1.6.14/ct1.h.gcc10	2011-12-23 20:30:53.000000000 +0100

+++ chemtool-1.6.14/ct1.h	2020-02-20 12:04:09.081966039 +0100

@@ -273,12 +273,12 @@ extern int nbonds;

 extern float importfactor;

 extern int importoffset;

-char **intype;

-char **inmode;

-int babelin;

-char **outtype;

-char **outmode;

-int babelout;

+extern char **intype;

+extern char **inmode;

+extern int babelin;

+extern char **outtype;

+extern char **outmode;

+extern int babelout;

 extern char *babel;

 extern GdkGC *mygc[8],*background_gc,*hlgc;

 extern int curpen;

diff -up chemtool-1.6.14/inout.c.gcc10 chemtool-1.6.14/inout.c

--- chemtool-1.6.14/inout.c.gcc10	2013-08-13 01:39:43.000000000 +0200

+++ chemtool-1.6.14/inout.c	2020-02-20 12:10:29.141059205 +0100

@@ -31,6 +31,12 @@ extern GdkFont *font[7],*smallfont[7],*s

 #endif

 static char babeloutp[4];

+int babelin;

+int babelout;

+char **inmode;

+char **intype;

+char **outmode;

+char **outtype;

 int

 save_mol (FILE * fp, int partial)