diff --git a/src/lv_draw/lv_draw_basic.c b/src/lv_draw/lv_draw_basic.c
index cf57b723a..c0e93b28e 100644
--- a/src/lv_draw/lv_draw_basic.c
+++ b/src/lv_draw/lv_draw_basic.c
@@ -290,10 +290,13 @@ void lv_draw_letter(const lv_point_t * pos_p, const lv_area_t * mask_p, const lv
     lv_coord_t col, row;
     uint8_t col_bit;
     uint8_t col_byte_cnt;
-    uint8_t width_byte_scr =
-        letter_w >> 3; /*Width in bytes (on the screen finally) (e.g. w = 11 -> 2 bytes wide)*/
+
+    /*Width in bytes (on the screen finally) (e.g. w = 11 -> 2 bytes wide)*/
+    uint8_t width_byte_scr = letter_w >> 3;
     if(letter_w & 0x7) width_byte_scr++;
-    uint8_t width_byte_bpp = (letter_w * bpp) >> 3; /*Letter width in byte. Real width in the font*/
+
+    /*Letter width in byte. Real width in the font*/
+    uint8_t width_byte_bpp = (letter_w * bpp) >> 3;
     if((letter_w * bpp) & 0x7) width_byte_bpp++;
 
     /* Calculate the col/row start/end on the map*/
@@ -332,12 +335,16 @@ void lv_draw_letter(const lv_point_t * pos_p, const lv_area_t * mask_p, const lv
                                            (col + pos_x) - vdb->area.x1,
                                            (row + pos_y) - vdb->area.y1, color, px_opa);
                 } else {
+                    if(px_opa > LV_OPA_MAX) *vdb_buf_tmp = color;
+                    else if(px_opa < LV_OPA_MIN) continue;
+                    else {
 #if LV_COLOR_SCREEN_TRANSP == 0
-                    *vdb_buf_tmp = lv_color_mix(color, *vdb_buf_tmp, px_opa);
+                        *vdb_buf_tmp = lv_color_mix(color, *vdb_buf_tmp, px_opa);
 #else
-                    *vdb_buf_tmp =
-                        color_mix_2_alpha(*vdb_buf_tmp, (*vdb_buf_tmp).alpha, color, px_opa);
+                        *vdb_buf_tmp =
+                                color_mix_2_alpha(*vdb_buf_tmp, (*vdb_buf_tmp).alpha, color, px_opa);
 #endif
+                    }
                 }
             }