diff --git a/doc/flatpak-manifest.xml b/doc/flatpak-manifest.xml
index 39e11041..0796e4a6 100644
--- a/doc/flatpak-manifest.xml
+++ b/doc/flatpak-manifest.xml
@@ -471,7 +471,7 @@
               Additionally the standard flatpak extension properties
               are supported, and put directly into the metadata file:
               autodelete, no-autodownload, subdirectories,
-              add-ld-path, download-if, enable-if, merge-dirs,
+              add-ld-path, download-if, enable-if, autoprune-unless, merge-dirs,
               subdirectory-suffix, locale-subset, version, versions.
               See the flatpak metadata documentation for more information on these.
             </para>
diff --git a/src/builder-extension.c b/src/builder-extension.c
index a2bd8186..411c27fe 100644
--- a/src/builder-extension.c
+++ b/src/builder-extension.c
@@ -49,6 +49,7 @@ struct BuilderExtension
   char           *add_ld_path;
   char           *download_if;
   char           *enable_if;
+  char           *autoprune_unless;
   char           *merge_dirs;
   char           *subdirectory_suffix;
   char           *version;
@@ -71,6 +72,7 @@ enum {
   PROP_ADD_LD_PATH,
   PROP_DOWNLOAD_IF,
   PROP_ENABLE_IF,
+  PROP_AUTOPRUNE_UNLESS,
   PROP_MERGE_DIRS,
   PROP_NO_AUTODOWNLOAD,
   PROP_LOCALE_SUBSET,
@@ -92,6 +94,7 @@ builder_extension_finalize (GObject *object)
   g_free (self->add_ld_path);
   g_free (self->download_if);
   g_free (self->enable_if);
+  g_free (self->autoprune_unless);
   g_free (self->merge_dirs);
   g_free (self->subdirectory_suffix);
   g_free (self->version);
@@ -150,6 +153,10 @@ builder_extension_get_property (GObject    *object,
       g_value_set_string (value, self->enable_if);
       break;
 
+    case PROP_AUTOPRUNE_UNLESS:
+      g_value_set_string (value, self->autoprune_unless);
+      break;
+
     case PROP_MERGE_DIRS:
       g_value_set_string (value, self->merge_dirs);
       break;
@@ -225,6 +232,11 @@ builder_extension_set_property (GObject      *object,
       self->enable_if = g_value_dup_string (value);
       break;
 
+  case PROP_AUTOPRUNE_UNLESS:
+      g_clear_pointer (&self->autoprune_unless, g_free);
+      self->autoprune_unless = g_value_dup_string (value);
+      break;
+
     case PROP_MERGE_DIRS:
       g_clear_pointer (&self->merge_dirs, g_free);
       self->merge_dirs = g_value_dup_string (value);
@@ -329,6 +341,13 @@ builder_extension_class_init (BuilderExtensionClass *klass)
                                                         "",
                                                         NULL,
                                                         G_PARAM_READWRITE));
+  g_object_class_install_property (object_class,
+                                   PROP_AUTOPRUNE_UNLESS,
+                                   g_param_spec_string ("autoprune-unless",
+                                                        "",
+                                                        "",
+                                                        NULL,
+                                                        G_PARAM_READWRITE));
   g_object_class_install_property (object_class,
                                    PROP_MERGE_DIRS,
                                    g_param_spec_string ("merge-dirs",
@@ -445,6 +464,7 @@ builder_extension_add_finish_args (BuilderExtension  *self,
   add_arg (self, args, FLATPAK_METADATA_KEY_ADD_LD_PATH, self->add_ld_path);
   add_arg (self, args, FLATPAK_METADATA_KEY_DOWNLOAD_IF, self->download_if);
   add_arg (self, args, FLATPAK_METADATA_KEY_ENABLE_IF, self->enable_if);
+  add_arg (self, args, FLATPAK_METADATA_KEY_AUTOPRUNE_UNLESS, self->autoprune_unless);
   add_arg (self, args, FLATPAK_METADATA_KEY_MERGE_DIRS, self->merge_dirs);
   add_arg (self, args, FLATPAK_METADATA_KEY_SUBDIRECTORY_SUFFIX, self->subdirectory_suffix);
   add_arg (self, args, FLATPAK_METADATA_KEY_VERSION, self->version);
@@ -467,6 +487,7 @@ builder_extension_checksum (BuilderExtension  *self,
   builder_cache_checksum_str (cache, self->add_ld_path);
   builder_cache_checksum_str (cache, self->download_if);
   builder_cache_checksum_str (cache, self->enable_if);
+  builder_cache_checksum_str (cache, self->autoprune_unless);
   builder_cache_checksum_str (cache, self->merge_dirs);
   builder_cache_checksum_str (cache, self->subdirectory_suffix);
   builder_cache_checksum_str (cache, self->version);
diff --git a/src/builder-flatpak-utils.h b/src/builder-flatpak-utils.h
index dc3865cf..5f44f114 100644
--- a/src/builder-flatpak-utils.h
+++ b/src/builder-flatpak-utils.h
@@ -45,6 +45,7 @@ typedef void (*FlatpakLoadUriProgress) (guint64 downloaded_bytes,
 #define FLATPAK_METADATA_KEY_DIRECTORY "directory"
 #define FLATPAK_METADATA_KEY_DOWNLOAD_IF "download-if"
 #define FLATPAK_METADATA_KEY_ENABLE_IF "enable-if"
+#define FLATPAK_METADATA_KEY_AUTOPRUNE_UNLESS "autoprune-unless"
 #define FLATPAK_METADATA_KEY_MERGE_DIRS "merge-dirs"
 #define FLATPAK_METADATA_KEY_NO_AUTODOWNLOAD "no-autodownload"
 #define FLATPAK_METADATA_KEY_LOCALE_SUBSET "locale-subset"