diff --git a/frontend/apps/reader/modules/readerhighlight.lua b/frontend/apps/reader/modules/readerhighlight.lua
index e65fe21f2..3d1a3328f 100644
--- a/frontend/apps/reader/modules/readerhighlight.lua
+++ b/frontend/apps/reader/modules/readerhighlight.lua
@@ -651,13 +651,13 @@ If you wish your highlights to be saved in the document, just move it to a writa
                     end,
                 },
                 {
-                    text = _("Delete all highlights from pdf file"),
+                    text = _("Delete all highlights from PDF file"),
                     enabled_func = function()
                         return self.highlight_write_into_pdf and self.ui.annotation:getNumberOfHighlightsAndNotes() > 0
                     end,
                     callback = function()
                         UIManager:show(ConfirmBox:new{
-                            text = _("Are you sure you want to delete all KOReader highlights from pdf file?"),
+                            text = _("Are you sure you want to delete all KOReader highlights from PDF file?"),
                             icon = "texture-box",
                             ok_callback = function()
                                 local count = 0
@@ -668,8 +668,8 @@ If you wish your highlights to be saved in the document, just move it to a writa
                                     end
                                 end
                                 UIManager:show(Notification:new{
-                                    text = T(N_("1 highlight deleted from pdf file",
-                                        "%1 highlights deleted from pdf file", count), count),
+                                    text = T(N_("1 highlight deleted from PDF file",
+                                        "%1 highlights deleted from PDF file", count), count),
                                 })
                             end,
                         })