diff --git a/src/stdio/src/FibreIO/FibreScan.h b/src/stdio/src/FibreIO/FibreScan.h
index e59f6805..01c8b648 100644
--- a/src/stdio/src/FibreIO/FibreScan.h
+++ b/src/stdio/src/FibreIO/FibreScan.h
@@ -52,7 +52,7 @@ extern int FibreScanlex(void);
 extern void doScan( FILE *stream);
 
 extern int boolval;
-extern char byteval;
+extern signed char byteval;
 extern short shortval;
 extern int intval;
 extern long longval;
@@ -67,7 +67,7 @@ extern double doubleval;
 extern char *stringval;
 extern double *doublearray;
 extern float *floatarray;
-extern char *bytearray;
+extern signed char *bytearray;
 extern short *shortarray;
 extern int *intarray;
 extern long *longarray;
diff --git a/src/stdio/src/FibreIO/FibreScan.y b/src/stdio/src/FibreIO/FibreScan.y
index 3804d793..9d392973 100644
--- a/src/stdio/src/FibreIO/FibreScan.y
+++ b/src/stdio/src/FibreIO/FibreScan.y
@@ -23,7 +23,7 @@ enum READMODE {
 };
 
 int     boolval;
-char    byteval;
+signed char    byteval;
 short   shortval;
 int     intval;
 long    longval;
@@ -38,7 +38,7 @@ double  doubleval;
 char    *stringval;
 double  *doublearray;
 float   *floatarray;
-char    *bytearray;
+signed char *bytearray;
 short   *shortarray;
 int     *intarray;
 long    *longarray;
@@ -267,7 +267,7 @@ parse_scalar: NUM
                     yyerror( "byte numeric expected!");
                   }
                   else {
-                    bytearray = (char *) SAC_MALLOC( sizeof( char));
+                    bytearray = (signed char *) SAC_MALLOC( sizeof( signed char));
                     *bytearray = $1;
                   }
                  got_scalar = 1;
@@ -485,7 +485,7 @@ array: SQBR_L desc COLON
            }
            switch( mode) {
              case byte_mode:
-               bytearray = (char *) SAC_MALLOC( size * sizeof( char));
+               bytearray = (signed char *) SAC_MALLOC( size * sizeof( signed char));
                break;
              case short_mode:
                shortarray = (short *) SAC_MALLOC( size * sizeof( short));
diff --git a/src/system/src/GetOpt/getopt.c b/src/system/src/GetOpt/getopt.c
index 8bf9517a..3c10dbe0 100644
--- a/src/system/src/GetOpt/getopt.c
+++ b/src/system/src/GetOpt/getopt.c
@@ -143,7 +143,7 @@ char getopt_sac(const char *opts)
                 SAC_optopt = arg[SAC_argind];
             }
 
-            char *p;
+            const char *p;
 
             if (SAC_optopt == ':' ||
                 SAC_optopt == '\0' ||