diff --git a/compiler/libpc300/sc1.c b/compiler/libpc300/sc1.c
index 8a43a125..6fc5aaa3 100755
--- a/compiler/libpc300/sc1.c
+++ b/compiler/libpc300/sc1.c
@@ -1108,7 +1108,11 @@ static void parseoptions(int argc,char **argv,char *oname,char *ename,char *pnam
         skipinput=atoi(option_value(ptr));
         break;
       case 't':
-        sc_tabsize=atoi(option_value(ptr));
+        i=atoi(option_value(ptr));
+		if (i>0)
+		  sc_tabsize=i;
+		else
+		  about();
         break;
       case 'v':
         verbosity= isdigit(*option_value(ptr)) ? atoi(option_value(ptr)) : 2;
diff --git a/compiler/libpc300/sc2.c b/compiler/libpc300/sc2.c
index bb48e71e..2017d4a4 100755
--- a/compiler/libpc300/sc2.c
+++ b/compiler/libpc300/sc2.c
@@ -1131,7 +1131,8 @@ static int command(void)
         } else if (strcmp(str,"tabsize")==0) {
           cell val;
           preproc_expr(&val,NULL);
-          sc_tabsize=(int)val;
+		  if (val>0)
+		    sc_tabsize=(int)val;
         } else if (strcmp(str,"align")==0) {
           sc_alignnext=TRUE;
         } else if (strcmp(str,"unused")==0) {