diff --git a/kiwixbuild/dependencies/base.py b/kiwixbuild/dependencies/base.py
index eef32d4..0015c19 100644
--- a/kiwixbuild/dependencies/base.py
+++ b/kiwixbuild/dependencies/base.py
@@ -286,6 +286,8 @@ class Builder:
     def set_flatpak_buildsystem(self, module):
         if getattr(self, 'flatpak_buildsystem', None):
             module['buildsystem'] = self.flatpak_buildsystem
+        if getattr(self, 'subsource_dir', None):
+            module['subdir'] = self.subsource_dir
         if getattr(self, 'configure_option', ''):
             module['config-opts'] = self.configure_option.split(' ')
 
diff --git a/kiwixbuild/flatpak_builder.py b/kiwixbuild/flatpak_builder.py
index 7c8f893..f0c4a59 100644
--- a/kiwixbuild/flatpak_builder.py
+++ b/kiwixbuild/flatpak_builder.py
@@ -139,8 +139,6 @@ class FlatpakBuilder:
         steps = remove_duplicates(target_steps())
         modules = OrderedDict()
         for stepDef in steps:
-            if stepDef[1] == 'zstd':
-                continue
             module = modules.setdefault(stepDef[1], {})
             module['name'] = stepDef[1]
             if stepDef[0] == 'source':