diff --git a/app/flatpak-builtins-build-init.c b/app/flatpak-builtins-build-init.c
index ce5c725e4..e6f54b3e4 100644
--- a/app/flatpak-builtins-build-init.c
+++ b/app/flatpak-builtins-build-init.c
@@ -32,12 +32,14 @@
 #include "flatpak-builtins.h"
 #include "flatpak-builtins-utils.h"
 #include "flatpak-utils.h"
+#include "flatpak-run.h"
 
 static char *opt_arch;
 static char *opt_var;
 static char *opt_type;
 static char *opt_sdk_dir;
 static char **opt_sdk_extensions;
+static char **opt_extensions;
 static char **opt_tags;
 static char *opt_extension_tag;
 static char *opt_base;
@@ -57,6 +59,7 @@ static GOptionEntry options[] = {
   { "type", 0, 0, G_OPTION_ARG_STRING, &opt_type, N_("Specify the build type (app, runtime, extension)"), N_("TYPE") },
   { "tag", 0, 0, G_OPTION_ARG_STRING_ARRAY, &opt_tags, N_("Add a tag"), N_("TAG") },
   { "sdk-extension", 0, 0, G_OPTION_ARG_STRING_ARRAY, &opt_sdk_extensions, N_("Include this sdk extension in /usr"), N_("EXTENSION") },
+  { "extension", 0, 0, G_OPTION_ARG_STRING_ARRAY, &opt_extensions, N_("Add extension point info"),  N_("NAME=VARIABLE[=VALUE]") },
   { "sdk-dir", 0, 0, G_OPTION_ARG_STRING, &opt_sdk_dir, N_("Where to store sdk (defaults to 'usr')"), N_("DIR") },
   { "update", 0, 0, G_OPTION_ARG_NONE, &opt_update, N_("Re-initialize the sdk/var"), NULL },
   { NULL }
@@ -186,6 +189,9 @@ flatpak_builtin_build_init (int argc, char **argv, GCancellable *cancellable, GE
   gboolean is_app = FALSE;
   gboolean is_extension = FALSE;
   gboolean is_runtime = FALSE;
+  g_autoptr(GKeyFile) keyfile = g_key_file_new ();
+  g_autofree char *keyfile_data = NULL;
+  gsize keyfile_data_len;
 
   context = g_option_context_new (_("DIRECTORY APPNAME SDK RUNTIME [BRANCH] - Initialize a directory for building"));
   g_option_context_set_translation_domain (context, GETTEXT_PACKAGE);
@@ -223,6 +229,7 @@ flatpak_builtin_build_init (int argc, char **argv, GCancellable *cancellable, GE
   if (!flatpak_is_valid_name (app_id, &my_error))
     return flatpak_fail (error, _("'%s' is not a valid application name: %s"), app_id, my_error->message);
 
+
   kinds = FLATPAK_KINDS_RUNTIME;
   sdk_dir = flatpak_find_installed_pref (sdk_pref, kinds, opt_arch, default_branch, TRUE, FALSE, FALSE, NULL,
                                          &sdk_ref, cancellable, error);
@@ -390,8 +397,30 @@ flatpak_builtin_build_init (int argc, char **argv, GCancellable *cancellable, GE
                               optional_extension_tag);
     }
 
+  /* Do the rest of the work as a keyfile, as we need things like full escaping, etc.
+   * We should probably do everything this way actually...   */
+  if (!g_key_file_load_from_data (keyfile, metadata_contents->str, metadata_contents->len, 0, NULL))
+    return flatpak_fail (error, "Internal error parsing generated keyfile");
+
+  for (i = 0; opt_extensions != NULL && opt_extensions[i] != NULL; i++)
+    {
+      g_auto(GStrv) elements = NULL;
+      g_autofree char *groupname = NULL;
+
+      elements = g_strsplit (opt_extensions[i], "=", 3);
+      if (g_strv_length (elements) < 2)
+        return flatpak_fail (error, _("Too few elements in --extension argument %s, format should be NAME=VAR[=VALUE]"), opt_extensions[i]);
+
+      groupname = g_strconcat (FLATPAK_METADATA_GROUP_PREFIX_EXTENSION,
+                               elements[0], NULL);
+
+      g_key_file_set_string (keyfile, groupname, elements[1], elements[2] ? elements[2] : "true");
+    }
+
+  keyfile_data = g_key_file_to_data (keyfile, &keyfile_data_len, NULL);
+
   if (!g_file_replace_contents (metadata_file,
-                                metadata_contents->str, metadata_contents->len, NULL, FALSE,
+                                keyfile_data, keyfile_data_len, NULL, FALSE,
                                 G_FILE_CREATE_REPLACE_DESTINATION,
                                 NULL, cancellable, error))
     return FALSE;
diff --git a/doc/flatpak-build-init.xml b/doc/flatpak-build-init.xml
index 620b66fba..25a2e747a 100644
--- a/doc/flatpak-build-init.xml
+++ b/doc/flatpak-build-init.xml
@@ -126,6 +126,14 @@
                 </para></listitem>
             </varlistentry>
 
+            <varlistentry>
+                <term><option>--extension=NAME=VARIABLE[=VALUE]</option></term>
+
+                <listitem><para>
+                  Add extension point info.
+                </para></listitem>
+            </varlistentry>
+
             <varlistentry>
                 <term><option>--sdk-dir</option></term>