diff --git a/tool/update-deps b/tool/update-deps
index c308f35195..ccfc160e42 100755
--- a/tool/update-deps
+++ b/tool/update-deps
@@ -238,6 +238,10 @@ DEPENDENCIES_SECTION_END_MARK = "\# AUTOGENERATED DEPENDENCIES END\n"
 
 def init_global
   ENV['LC_ALL'] = 'C'
+  if mkflag = ENV['GNUMAKEFLAGS'] and mkflag.sub!(/(\A|\s+)-j\d*(?=\s+|\z)/, '')
+    mkflag.strip!
+    ENV['GNUMAKEFLAGS'] = mkflag
+  end
 
   $opt_fix = false
   $opt_a = false