diff --git a/lib/fort.c b/lib/fort.c
index 353f917..cd40784 100644
--- a/lib/fort.c
+++ b/lib/fort.c
@@ -1961,20 +1961,20 @@ int ft_add_separator(ft_table_t *table)
 
 
 
-struct ft_border_style *FT_BASIC_STYLE = (struct ft_border_style *) &FORT_BASIC_STYLE;
-struct ft_border_style *FT_BASIC2_STYLE = (struct ft_border_style *) &FORT_BASIC2_STYLE;
-struct ft_border_style *FT_SIMPLE_STYLE = (struct ft_border_style *) &FORT_SIMPLE_STYLE;
-struct ft_border_style *FT_PLAIN_STYLE = (struct ft_border_style *) &FORT_PLAIN_STYLE;
-struct ft_border_style *FT_DOT_STYLE = (struct ft_border_style *) &FORT_DOT_STYLE;
-struct ft_border_style *FT_EMPTY_STYLE  = (struct ft_border_style *) &FORT_EMPTY_STYLE;
-struct ft_border_style *FT_SOLID_STYLE  = (struct ft_border_style *) &FORT_SOLID_STYLE;
-struct ft_border_style *FT_SOLID_ROUND_STYLE  = (struct ft_border_style *) &FORT_SOLID_ROUND_STYLE;
-struct ft_border_style *FT_NICE_STYLE  = (struct ft_border_style *) &FORT_NICE_STYLE;
-struct ft_border_style *FT_DOUBLE_STYLE  = (struct ft_border_style *) &FORT_DOUBLE_STYLE;
-struct ft_border_style *FT_DOUBLE2_STYLE  = (struct ft_border_style *) &FORT_DOUBLE2_STYLE;
-struct ft_border_style *FT_BOLD_STYLE  = (struct ft_border_style *) &FORT_BOLD_STYLE;
-struct ft_border_style *FT_BOLD2_STYLE  = (struct ft_border_style *) &FORT_BOLD2_STYLE;
-struct ft_border_style *FT_FRAME_STYLE  = (struct ft_border_style *) &FORT_FRAME_STYLE;
+struct ft_border_style *const FT_BASIC_STYLE = (struct ft_border_style *) &FORT_BASIC_STYLE;
+struct ft_border_style *const FT_BASIC2_STYLE = (struct ft_border_style *) &FORT_BASIC2_STYLE;
+struct ft_border_style *const FT_SIMPLE_STYLE = (struct ft_border_style *) &FORT_SIMPLE_STYLE;
+struct ft_border_style *const FT_PLAIN_STYLE = (struct ft_border_style *) &FORT_PLAIN_STYLE;
+struct ft_border_style *const FT_DOT_STYLE = (struct ft_border_style *) &FORT_DOT_STYLE;
+struct ft_border_style *const FT_EMPTY_STYLE  = (struct ft_border_style *) &FORT_EMPTY_STYLE;
+struct ft_border_style *const FT_SOLID_STYLE  = (struct ft_border_style *) &FORT_SOLID_STYLE;
+struct ft_border_style *const FT_SOLID_ROUND_STYLE  = (struct ft_border_style *) &FORT_SOLID_ROUND_STYLE;
+struct ft_border_style *const FT_NICE_STYLE  = (struct ft_border_style *) &FORT_NICE_STYLE;
+struct ft_border_style *const FT_DOUBLE_STYLE  = (struct ft_border_style *) &FORT_DOUBLE_STYLE;
+struct ft_border_style *const FT_DOUBLE2_STYLE  = (struct ft_border_style *) &FORT_DOUBLE2_STYLE;
+struct ft_border_style *const FT_BOLD_STYLE  = (struct ft_border_style *) &FORT_BOLD_STYLE;
+struct ft_border_style *const FT_BOLD2_STYLE  = (struct ft_border_style *) &FORT_BOLD2_STYLE;
+struct ft_border_style *const FT_FRAME_STYLE  = (struct ft_border_style *) &FORT_FRAME_STYLE;
 
 
 
diff --git a/lib/fort.h b/lib/fort.h
index ec01bbd..a172482 100644
--- a/lib/fort.h
+++ b/lib/fort.h
@@ -605,20 +605,20 @@ struct ft_border_style {
  * @name Built-in table border styles.
  * @{
  */
-extern struct ft_border_style *FT_BASIC_STYLE;
-extern struct ft_border_style *FT_BASIC2_STYLE;
-extern struct ft_border_style *FT_SIMPLE_STYLE;
-extern struct ft_border_style *FT_PLAIN_STYLE;
-extern struct ft_border_style *FT_DOT_STYLE;
-extern struct ft_border_style *FT_EMPTY_STYLE;
-extern struct ft_border_style *FT_SOLID_STYLE;
-extern struct ft_border_style *FT_SOLID_ROUND_STYLE;
-extern struct ft_border_style *FT_NICE_STYLE;
-extern struct ft_border_style *FT_DOUBLE_STYLE;
-extern struct ft_border_style *FT_DOUBLE2_STYLE;
-extern struct ft_border_style *FT_BOLD_STYLE;
-extern struct ft_border_style *FT_BOLD2_STYLE;
-extern struct ft_border_style *FT_FRAME_STYLE;
+extern struct ft_border_style *const FT_BASIC_STYLE;
+extern struct ft_border_style *const FT_BASIC2_STYLE;
+extern struct ft_border_style *const FT_SIMPLE_STYLE;
+extern struct ft_border_style *const FT_PLAIN_STYLE;
+extern struct ft_border_style *const FT_DOT_STYLE;
+extern struct ft_border_style *const FT_EMPTY_STYLE;
+extern struct ft_border_style *const FT_SOLID_STYLE;
+extern struct ft_border_style *const FT_SOLID_ROUND_STYLE;
+extern struct ft_border_style *const FT_NICE_STYLE;
+extern struct ft_border_style *const FT_DOUBLE_STYLE;
+extern struct ft_border_style *const FT_DOUBLE2_STYLE;
+extern struct ft_border_style *const FT_BOLD_STYLE;
+extern struct ft_border_style *const FT_BOLD2_STYLE;
+extern struct ft_border_style *const FT_FRAME_STYLE;
 /** @} */
 
 
diff --git a/src/fort_impl.c b/src/fort_impl.c
index 1937c2b..52aa8d4 100644
--- a/src/fort_impl.c
+++ b/src/fort_impl.c
@@ -806,20 +806,20 @@ int ft_add_separator(ft_table_t *table)
 
 
 
-struct ft_border_style *FT_BASIC_STYLE = (struct ft_border_style *) &FORT_BASIC_STYLE;
-struct ft_border_style *FT_BASIC2_STYLE = (struct ft_border_style *) &FORT_BASIC2_STYLE;
-struct ft_border_style *FT_SIMPLE_STYLE = (struct ft_border_style *) &FORT_SIMPLE_STYLE;
-struct ft_border_style *FT_PLAIN_STYLE = (struct ft_border_style *) &FORT_PLAIN_STYLE;
-struct ft_border_style *FT_DOT_STYLE = (struct ft_border_style *) &FORT_DOT_STYLE;
-struct ft_border_style *FT_EMPTY_STYLE  = (struct ft_border_style *) &FORT_EMPTY_STYLE;
-struct ft_border_style *FT_SOLID_STYLE  = (struct ft_border_style *) &FORT_SOLID_STYLE;
-struct ft_border_style *FT_SOLID_ROUND_STYLE  = (struct ft_border_style *) &FORT_SOLID_ROUND_STYLE;
-struct ft_border_style *FT_NICE_STYLE  = (struct ft_border_style *) &FORT_NICE_STYLE;
-struct ft_border_style *FT_DOUBLE_STYLE  = (struct ft_border_style *) &FORT_DOUBLE_STYLE;
-struct ft_border_style *FT_DOUBLE2_STYLE  = (struct ft_border_style *) &FORT_DOUBLE2_STYLE;
-struct ft_border_style *FT_BOLD_STYLE  = (struct ft_border_style *) &FORT_BOLD_STYLE;
-struct ft_border_style *FT_BOLD2_STYLE  = (struct ft_border_style *) &FORT_BOLD2_STYLE;
-struct ft_border_style *FT_FRAME_STYLE  = (struct ft_border_style *) &FORT_FRAME_STYLE;
+struct ft_border_style *const FT_BASIC_STYLE = (struct ft_border_style *) &FORT_BASIC_STYLE;
+struct ft_border_style *const FT_BASIC2_STYLE = (struct ft_border_style *) &FORT_BASIC2_STYLE;
+struct ft_border_style *const FT_SIMPLE_STYLE = (struct ft_border_style *) &FORT_SIMPLE_STYLE;
+struct ft_border_style *const FT_PLAIN_STYLE = (struct ft_border_style *) &FORT_PLAIN_STYLE;
+struct ft_border_style *const FT_DOT_STYLE = (struct ft_border_style *) &FORT_DOT_STYLE;
+struct ft_border_style *const FT_EMPTY_STYLE  = (struct ft_border_style *) &FORT_EMPTY_STYLE;
+struct ft_border_style *const FT_SOLID_STYLE  = (struct ft_border_style *) &FORT_SOLID_STYLE;
+struct ft_border_style *const FT_SOLID_ROUND_STYLE  = (struct ft_border_style *) &FORT_SOLID_ROUND_STYLE;
+struct ft_border_style *const FT_NICE_STYLE  = (struct ft_border_style *) &FORT_NICE_STYLE;
+struct ft_border_style *const FT_DOUBLE_STYLE  = (struct ft_border_style *) &FORT_DOUBLE_STYLE;
+struct ft_border_style *const FT_DOUBLE2_STYLE  = (struct ft_border_style *) &FORT_DOUBLE2_STYLE;
+struct ft_border_style *const FT_BOLD_STYLE  = (struct ft_border_style *) &FORT_BOLD_STYLE;
+struct ft_border_style *const FT_BOLD2_STYLE  = (struct ft_border_style *) &FORT_BOLD2_STYLE;
+struct ft_border_style *const FT_FRAME_STYLE  = (struct ft_border_style *) &FORT_FRAME_STYLE;