diff --git a/apps/lang/lang.make b/apps/lang/lang.make
index 6465b426b7..cee2456b5d 100644
--- a/apps/lang/lang.make
+++ b/apps/lang/lang.make
@@ -31,11 +31,19 @@ $(BUILDDIR)/lang/max_language_size.h: $(LANGOBJ) $(BUILDDIR)/apps/lang/voicestri
 $(BUILDDIR)/lang/lang_core.o: $(BUILDDIR)/lang/lang.h $(BUILDDIR)/lang/lang_core.c
 	$(call PRINTS,CC lang_core.c)$(CC) $(CFLAGS) -c $(BUILDDIR)/lang/lang_core.c -o $@
 
-$(BUILDDIR)/lang/lang.h $(BUILDDIR)/lang/lang_core.c: $(APPSDIR)/lang/$(LANGUAGE).lang $(BUILDDIR)/apps/features
+# genlang creates *both* lang.c and lang.h but in Make there is no wat to express this rule
+# (multiple target rules DO NOT express that, they are a simple shortcut for multiple rules)
+# instead we pretend that genlang create lang_core.c and that lang.c depends from lang.h
+# it will work fine as long as one never manually removes lang.c and not lang.h, and it will avoid
+# race conditions such as running genlang twice or worse in parallel with other things!
+$(BUILDDIR)/lang/lang.h: $(APPSDIR)/lang/$(LANGUAGE).lang $(BUILDDIR)/apps/features
 	$(call PRINTS,GEN lang.h)
 	$(SILENT)for f in `cat $(BUILDDIR)/apps/features`; do feat="$$feat:$$f" ; done; \
 		perl -s $(TOOLSDIR)/genlang -p=$(BUILDDIR)/lang -t=$(MODELNAME)$$feat $<
+$(BUILDDIR)/lang/lang_core.c: $(BUILDDIR)/lang/lang.h
 
+# NOTE: for some weird reasons in GNU make, multi targets rules WITH patterns actually express
+# the fact that the two files are created as the result of one invocation of the rule
 $(BUILDDIR)/%.lng $(BUILDDIR)/%.vstrings: $(ROOTDIR)/%.lang $(BUILDDIR)/apps/genlang-features
 	$(call PRINTS,GENLANG $(subst $(ROOTDIR)/,,$<))
 	$(SILENT)mkdir -p $(dir $@)