diff --git a/Makefile.in b/Makefile.in
index a9befca294b..1914ce340ac 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -79,7 +79,11 @@ $(S)config.stamp : $(S)configure $(S)Makefile.in
 define DEF_SUBMODULE_VARS
 DEPS_$(1) =
 CFLAGS_$(1) = -O2
-DONE_$(1) = $$(B)src/$(1)/$(1).dummy
+# any "done" dummy files must be named libSOMETHING.dummy. 
+#
+# We can't auto-compute this, because some modules have lib* prefix in
+# their name already, while others don't.
+DONE_$(1) = $$(B)src/$(1)/lib*.dummy
 DEPS_SUBMODULES += $(1)
 endef
 
diff --git a/mk/sub.mk b/mk/sub.mk
index 85ffc6c9f57..8b6a6e4019c 100644
--- a/mk/sub.mk
+++ b/mk/sub.mk
@@ -78,7 +78,7 @@ DEPS_rust-azure += \
 	rust-core-graphics \
 	rust-core-text \
 	rust-core-foundation \
-    skia \
+	skia \
 	$(NULL)
 
 DEPS_rust-cairo += \