diff --git a/Makefile b/Makefile
index d555bb2..373a861 100644
--- a/Makefile
+++ b/Makefile
@@ -79,7 +79,10 @@ romsubdir-%:
 
 ALL_SUBDIRS=$(TARGET_DIRS) $(patsubst %,pc-bios/%, $(ROMS))
 
-recurse-all: $(SUBDIR_RULES) $(ROMSUBDIR_RULES)
+# Some files are shared between the tools and the emulators.  So there
+# can be a race when the main makefile starts building xyz.o, while
+# the recursive make sees a partially built xyz.o and ar(1) fails.
+recurse-all: $(SUBDIR_RULES) $(ROMSUBDIR_RULES) | $(TOOLS)
 
 #######################################################################
 # QObject