diff --git a/autoload/gitgutter/diff.vim b/autoload/gitgutter/diff.vim
index 2deebe0..6325ca3 100644
--- a/autoload/gitgutter/diff.vim
+++ b/autoload/gitgutter/diff.vim
@@ -4,14 +4,6 @@ let s:nomodeline = (v:version > 703 || (v:version == 703 && has('patch442'))) ?
 
 let s:hunk_re = '^@@ -\(\d\+\),\?\(\d*\) +\(\d\+\),\?\(\d*\) @@'
 
-" True for git v1.7.2+.
-function! s:git_supports_command_line_config_override() abort
-  let [_, error_code] = gitgutter#utility#system(gitgutter#git().' -c foo.bar=baz --version')
-  return !error_code
-endfunction
-
-let s:c_flag = s:git_supports_command_line_config_override()
-
 let s:temp_from = tempname()
 let s:temp_buffer = tempname()
 let s:counter = 0
@@ -132,7 +124,7 @@ function! gitgutter#diff#run_diff(bufnr, from, preserve_full_diff) abort
 
   " Call git-diff.
   let cmd .= gitgutter#git().' --no-pager'
-  if s:c_flag
+  if gitgutter#utility#git_supports_command_line_config_override()
     let cmd .= ' -c "diff.autorefreshindex=0"'
     let cmd .= ' -c "diff.noprefix=false"'
     let cmd .= ' -c "core.safecrlf=false"'
diff --git a/autoload/gitgutter/utility.vim b/autoload/gitgutter/utility.vim
index 3577085..dcded00 100644
--- a/autoload/gitgutter/utility.vim
+++ b/autoload/gitgutter/utility.vim
@@ -6,6 +6,15 @@ function! gitgutter#utility#supports_overscore_sign()
   endif
 endfunction
 
+" True for git v1.7.2+.
+function! gitgutter#utility#git_supports_command_line_config_override() abort
+  if !exists('s:c_flag')
+    let [_, error_code] = gitgutter#utility#system(gitgutter#git().' -c foo.bar=baz --version')
+    let s:c_flag = !error_code
+  endif
+  return s:c_flag
+endfunction
+
 function! gitgutter#utility#setbufvar(buffer, varname, val)
   let buffer = +a:buffer
   " Default value for getbufvar() was introduced in Vim 7.3.831.