diff --git a/config/baseconfig.mk b/config/baseconfig.mk
index b7adc7aa8c5b..78e50bbfbd40 100644
--- a/config/baseconfig.mk
+++ b/config/baseconfig.mk
@@ -29,7 +29,7 @@ endif
 endif # WINNT
 
 ifdef .PYMAKE
-include_deps = $(eval -includedeps $(1))
+include_deps = $(eval $(if $(2),,-)includedeps $(1))
 else
-include_deps = $(eval -include $(1))
+include_deps = $(eval $(if $(2),,-)include $(1))
 endif
diff --git a/dom/bindings/Makefile.in b/dom/bindings/Makefile.in
index 3f008078fd5c..f9da051c61f0 100644
--- a/dom/bindings/Makefile.in
+++ b/dom/bindings/Makefile.in
@@ -58,11 +58,10 @@ codegen_dependencies := \
   $(GLOBAL_DEPS) \
   $(NULL)
 
-$(call include_deps,codegen.pp)
+# The 1 is to make codegen.pp not optional.
+$(call include_deps,codegen.pp,1)
 
-codegen.pp: codegen.done
-
-codegen.done: $(codegen_dependencies)
+codegen.pp: $(codegen_dependencies)
 	$(call py_action,webidl,$(srcdir))
 	@$(TOUCH) $@
 
diff --git a/dom/bindings/mozwebidlcodegen/__init__.py b/dom/bindings/mozwebidlcodegen/__init__.py
index 34b1f1bf8cbf..fdbb49164c94 100644
--- a/dom/bindings/mozwebidlcodegen/__init__.py
+++ b/dom/bindings/mozwebidlcodegen/__init__.py
@@ -546,7 +546,7 @@ def create_build_system_manager(topsrcdir, topobjdir, dist_dir):
         cache_dir=cache_dir,
         # The make rules include a codegen.pp file containing dependencies.
         make_deps_path=os.path.join(obj_dir, 'codegen.pp'),
-        make_deps_target='codegen.done',
+        make_deps_target='codegen.pp',
     )