diff --git a/frontend/document/credocument.lua b/frontend/document/credocument.lua
index e03998bb6..61e6bcdb2 100644
--- a/frontend/document/credocument.lua
+++ b/frontend/document/credocument.lua
@@ -1294,6 +1294,7 @@ end
 
 function CreDocument:register(registry)
     registry:addProvider("azw", "application/vnd.amazon.mobi8-ebook", self, 90)
+    registry:addProvider("azw", "application/x-mobi8-ebook", self, 90) -- Alternative mimetype for OPDS.
     registry:addProvider("chm", "application/vnd.ms-htmlhelp", self, 90)
     registry:addProvider("doc", "application/msword", self, 90)
     registry:addProvider("docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document", self, 90)
@@ -1301,6 +1302,7 @@ function CreDocument:register(registry)
     registry:addProvider("epub3", "application/epub+zip", self, 100)
     registry:addProvider("fb2", "application/fb2", self, 90)
     registry:addProvider("fb2.zip", "application/zip", self, 90)
+    registry:addProvider("fb2.zip", "application/fb2+zip", self, 90) -- Alternative mimetype for OPDS.
     registry:addProvider("fb3", "application/fb3", self, 90)
     registry:addProvider("htm", "text/html", self, 100)
     registry:addProvider("html", "text/html", self, 100)
diff --git a/frontend/document/djvudocument.lua b/frontend/document/djvudocument.lua
index 5979f277d..a0ca5366d 100644
--- a/frontend/document/djvudocument.lua
+++ b/frontend/document/djvudocument.lua
@@ -150,6 +150,8 @@ end
 
 function DjvuDocument:register(registry)
     registry:addProvider("djvu", "image/vnd.djvu", self, 100)
+    registry:addProvider("djvu", "application/djvu", self, 100) -- Alternative mimetype for OPDS.
+    registry:addProvider("djvu", "image/x-djvu", self, 100) -- Alternative mimetype for OPDS.
     registry:addProvider("djv", "image/vnd.djvu", self, 100)
 end
 
diff --git a/frontend/document/pdfdocument.lua b/frontend/document/pdfdocument.lua
index 2579e33e8..1087bbeb4 100644
--- a/frontend/document/pdfdocument.lua
+++ b/frontend/document/pdfdocument.lua
@@ -291,6 +291,7 @@ function PdfDocument:register(registry)
     --- Document types ---
     registry:addProvider("cbt", "application/vnd.comicbook+tar", self, 100)
     registry:addProvider("cbz", "application/vnd.comicbook+zip", self, 100)
+    registry:addProvider("cbz", "application/x-cbz", self, 100) -- Alternative mimetype for OPDS.
     registry:addProvider("epub", "application/epub+zip", self, 50)
     registry:addProvider("epub3", "application/epub+zip", self, 50)
     registry:addProvider("fb2", "application/fb2", self, 80)