diff --git a/Library/Homebrew/shims/super/cc b/Library/Homebrew/shims/super/cc
index a9dea3e8ed..0ea2f6e4e9 100755
--- a/Library/Homebrew/shims/super/cc
+++ b/Library/Homebrew/shims/super/cc
@@ -17,8 +17,8 @@ def mac?
   RUBY_PLATFORM[/darwin/]
 end
 
-def mojave_or_later?
-  mac? && RUBY_PLATFORM[/darwin\d+/][/\d+/].to_i >= 18
+def high_sierra_or_later?
+  mac? && RUBY_PLATFORM[/darwin\d+/][/\d+/].to_i >= 17
 end
 
 def linux?
@@ -187,7 +187,7 @@ class Cmd
       # clang doesn't support these flags
       args << arg unless tool =~ /^clang/
     when /-mmacosx-version-min=10\.(\d)/
-      arg = "-mmacosx-version-min=10.6" if mojave_or_later? && $1.to_i < 6
+      arg = "-mmacosx-version-min=10.9" if high_sierra_or_later? && $1.to_i < 9
       args << arg
     when "--fast-math"
       arg = "-ffast-math" if tool =~ /^clang/