diff --git a/functions.mk b/functions.mk
new file mode 100644
index 0000000..ba610f1
--- /dev/null
+++ b/functions.mk
@@ -0,0 +1,3 @@
+define tangle =
+emacs -Q -batch -l "ob-tangle" -eval "(org-babel-tangle-file \"$<\")"
+endef
diff --git a/mailcap/.gitignore b/mailcap/.gitignore
new file mode 100644
index 0000000..b733d69
--- /dev/null
+++ b/mailcap/.gitignore
@@ -0,0 +1 @@
+.mailcap
diff --git a/mailcap/.mailcap b/mailcap/.mailcap
deleted file mode 100644
index 3a78b82..0000000
--- a/mailcap/.mailcap
+++ /dev/null
@@ -1,5 +0,0 @@
-application/pdf; zathura %s
-image/*; gimp %s
-image/*; feh %s
-application/vnd.openxmlformats-officedocument.wordprocessingml.document; libreoffice %s
-application/vnd.openxmlformats-officedocument.spreadsheetml.sheet; libreoffice %s
diff --git a/mailcap/Makefile b/mailcap/Makefile
new file mode 100644
index 0000000..f69cced
--- /dev/null
+++ b/mailcap/Makefile
@@ -0,0 +1,6 @@
+include ../functions.mk
+
+files: .mailcap
+
+.mailcap: mailcap.org
+	$(call tangle)
diff --git a/mailcap/mailcap.org b/mailcap/mailcap.org
new file mode 100644
index 0000000..161b48d
--- /dev/null
+++ b/mailcap/mailcap.org
@@ -0,0 +1,29 @@
+#+TITLE: Mailcap
+#+PROPERTY: tangle .mailcap
+#+PROPERTY: padline no
+#+STARTUP: showall
+#+OPTIONS: author:nil num:nil toc:nil
+#+HTML_HEAD: <link href="https://ryuslash.org/org.css" rel="stylesheet" type="text/css" />
+
+This is mostly used, in my case, for telling Gnus how to open certain
+files.
+
+- Use [[https://pwmt.org/projects/zathura/][zathura]] to read PDF files.
+
+  #+BEGIN_SRC fundamental
+    application/pdf; zathura %s
+  #+END_SRC
+
+- Use [[http://www.gimp.org/][GIMP]] or [[http://feh.finalrewind.org/][feh]] to open any image files.
+
+  #+BEGIN_SRC fundamental
+    image/*; gimp %s
+    image/*; feh %s
+  #+END_SRC
+
+- Use [[https://www.libreoffice.org/][LibreOffice]] to open any ~.docx~ or ~.xlsx~ files.
+
+  #+BEGIN_SRC fundamental
+    application/vnd.openxmlformats-officedocument.wordprocessingml.document; libreoffice %s
+    application/vnd.openxmlformats-officedocument.spreadsheetml.sheet; libreoffice %s
+  #+END_SRC