diff --git a/Library/Homebrew/extend/ENV/super.rb b/Library/Homebrew/extend/ENV/super.rb
index aa12aa71c5..4c78898dac 100644
--- a/Library/Homebrew/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/ENV/super.rb
@@ -285,7 +285,7 @@ module Superenv
   end
 
   def permit_arch_flags
-    append "HOMEBREW_CCCFG", "K"
+    append "HOMEBREW_CCCFG", "K", ""
   end
 
   def m32
diff --git a/Library/Homebrew/extend/os/mac/extend/ENV/super.rb b/Library/Homebrew/extend/os/mac/extend/ENV/super.rb
index 841ff04202..1f5bb584c8 100644
--- a/Library/Homebrew/extend/os/mac/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/os/mac/extend/ENV/super.rb
@@ -139,6 +139,6 @@ module Superenv
   end
 
   def no_weak_imports
-    append "HOMEBREW_CCCFG", "w" if no_weak_imports_support?
+    append "HOMEBREW_CCCFG", "w", "" if no_weak_imports_support?
   end
 end