diff --git a/tool/generic_erb.rb b/tool/generic_erb.rb
index 6d97d21fb7..149de3b1b9 100644
--- a/tool/generic_erb.rb
+++ b/tool/generic_erb.rb
@@ -24,7 +24,7 @@ end
 unchanged = "unchanged"
 updated = "updated"
 if color or (color == nil && STDOUT.tty?)
-  if /\A(\e\[).*m\z/ =~ IO.popen("tput smso", "r", &:read)
+  if (/\A(\e\[).*m\z/ =~ IO.popen("tput smso", "r", err: IO::NULL, &:read) rescue nil)
     beg = $1
     colors = (colors = ENV['TEST_COLORS']) ? Hash[colors.scan(/(\w+)=([^:\n]*)/)] : {}
     reset = "#{beg}m"