diff --git a/Library/Formula/python.rb b/Library/Formula/python.rb
index 5a63ce1330..d4e7d4613f 100644
--- a/Library/Formula/python.rb
+++ b/Library/Formula/python.rb
@@ -241,7 +241,9 @@ def distutils_fix_stdenv
     # the needed includes with "-I" here to avoid this err:
     #     building dbm using ndbm
     #     error: /usr/include/zlib.h: No such file or directory
-    ENV.append "CPPFLAGS", "-I#{MacOS.sdk_path}/usr/include" unless MacOS::CLT.installed?
+    if OS.mac?
+        ENV.append "CPPFLAGS", "-I#{MacOS.sdk_path}/usr/include" unless MacOS::CLT.installed?
+    end
 
     # Don't use optimizations other than "-Os" here, because Python's distutils
     # remembers (hint: `python-config --cflags`) and reuses them for C
diff --git a/Library/Homebrew/extend/ENV/std.rb b/Library/Homebrew/extend/ENV/std.rb
index 5d94441053..5dd8b3c27a 100644
--- a/Library/Homebrew/extend/ENV/std.rb
+++ b/Library/Homebrew/extend/ENV/std.rb
@@ -200,11 +200,15 @@ def macosxsdk version=MacOS.version
 
   def minimal_optimization
     set_cflags "-Os #{SAFE_CFLAGS_FLAGS}"
-    macosxsdk unless MacOS::CLT.installed?
+    if OS.mac?
+        macosxsdk unless MacOS::CLT.installed?
+    end
   end
   def no_optimization
     set_cflags SAFE_CFLAGS_FLAGS
-    macosxsdk unless MacOS::CLT.installed?
+    if OS.mac?
+        macosxsdk unless MacOS::CLT.installed?
+    end
   end
 
   # Some configure scripts won't find libxml2 without help