diff --git a/Makefile b/Makefile
index 5a9ca7b..a4e0266 100644
--- a/Makefile
+++ b/Makefile
@@ -98,6 +98,9 @@ endif
 
 .PHONY: all clean install docs
 
+# Don't update archives in parallel, it's unsupported
+.NOTPARALLEL: $(LIBDIR)/libgray.a
+
 all: $(BINARIES) $(LIBRARIES)
 
 # Remove all generated files