diff --git a/Formula/t/travis.rb b/Formula/t/travis.rb
index 5da38c5679cf..583663cb385b 100644
--- a/Formula/t/travis.rb
+++ b/Formula/t/travis.rb
@@ -184,7 +184,7 @@ class Travis < Formula
   def install
     ENV["GEM_HOME"] = libexec
     # gem issue on Mojave
-    ENV["SDKROOT"] = MacOS.sdk_path if MacOS.version == :mojave
+    ENV["SDKROOT"] = MacOS.sdk_path if OS.mac? && MacOS.version == :mojave
 
     resources.each do |r|
       r.fetch