diff --git a/.github/workflows/buildtest.yml b/.github/workflows/buildtest.yml
index b094c4895..3f0a550da 100644
--- a/.github/workflows/buildtest.yml
+++ b/.github/workflows/buildtest.yml
@@ -10,25 +10,21 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
-        vim: [v8.2.0020, v9.0.0107, head]
+        vim: [v9.0.0107, v9.1.0100 ,head]
         type: [vim, macvim]
         download: [available]
         exclude:
           - os: ubuntu-latest
             # linux only vim/ macvim run as mac os
             type: macvim
-          - os: macos-latest
-            type: vim
-            # v8.2.1310 or later is required to build on macos-latest
-            vim: v8.2.0020
           - os: macos-latest
             type: macvim
             # macvim only head
-            vim: v8.2.0020
+            vim: v9.0.0107
           - os: macos-latest
             type: macvim
             # macvim only head
-            vim: v9.0.0107
+            vim: v9.1.0100
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.type }} ${{ matrix.vim }}/${{ matrix.os }} test
     env:
@@ -139,7 +135,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [windows-latest]
-        vim: [v8.2.0020, v9.0.0107, head]
+        vim: [v9.0.0107, v9.1.0100 ,head]
         type: [vim]
         download: [available]
     runs-on: ${{ matrix.os }}
diff --git a/README.md b/README.md
index 0000aedbc..820467bd2 100644
--- a/README.md
+++ b/README.md
@@ -6,10 +6,10 @@ A comprehensive Vim utility functions for Vim plugins.
 
 ## Requirements
 
-Modules in vital.vim basically support Vim 8.2 or later.
+Modules in vital.vim basically support Vim 9.0 or later.
 We guarantee that the following versions of Vim are supported:
-* The latest major version (9.0.\*)
-* The previous major version (8.2.\*)
+* The latest major version (9.1.\*)
+* The previous major version (9.0.\*)
 
 And some modules have stricter requirements and additional dependencies.
 Please read the docs of each module before using them.
diff --git a/autoload/vital/__vital__/Bitwise.vim b/autoload/vital/__vital__/Bitwise.vim
index 487deb567..feee04448 100644
--- a/autoload/vital/__vital__/Bitwise.vim
+++ b/autoload/vital/__vital__/Bitwise.vim
@@ -24,34 +24,13 @@ function! s:compare(a, b) abort
   endif
 endfunction
 
-if has("patch-8.2.5003")
-  function! s:lshift(a, n) abort
-    return a:a << and(a:n, s:mask)
-  endfunction
-
-  function! s:rshift(a, n) abort
-    return a:a >> and(a:n, s:mask)
-  endfunction
-else
-  let s:pow2 = [1]
-  for s:i in range(s:mask)
-    call add(s:pow2, s:pow2[-1] * 2)
-  endfor
-  unlet s:i
-
-  let s:min = s:pow2[-1]
-
-  function! s:lshift(a, n) abort
-    return a:a * s:pow2[and(a:n, s:mask)]
-  endfunction
+function! s:lshift(a, n) abort
+  return a:a << and(a:n, s:mask)
+endfunction
 
-  function! s:rshift(a, n) abort
-    let n = and(a:n, s:mask)
-    return n == 0 ? a:a :
-    \  a:a < 0 ? (a:a - s:min) / s:pow2[n] + s:pow2[-2] / s:pow2[n - 1]
-    \          : a:a / s:pow2[n]
-  endfunction
-endif
+function! s:rshift(a, n) abort
+  return a:a >> and(a:n, s:mask)
+endfunction
 
 " 32bit or 64bit specific method
 " define sign_extension
@@ -60,11 +39,7 @@ if has('num64')
   " NOTE:
   " An int literal larger than or equal to 0x8000000000000000 will be rounded
   " to 0x7FFFFFFFFFFFFFFF after Vim 8.0.0219, so create it without literal
-  if has("patch-8.2.5003")
-    let s:xFFFFFFFF00000000 = 0xFFFFFFFF << and(32, s:mask)
-  else
-    let s:xFFFFFFFF00000000 = 0xFFFFFFFF * s:pow2[and(32, s:mask)]
-  endif
+  let s:xFFFFFFFF00000000 = 0xFFFFFFFF << and(32, s:mask)
   function! s:sign_extension(n) abort
     if and(a:n, 0x80000000)
       return or(a:n, s:xFFFFFFFF00000000)
diff --git a/autoload/vital/__vital__/Color.vim b/autoload/vital/__vital__/Color.vim
index 216ff17ae..f3f8c3644 100644
--- a/autoload/vital/__vital__/Color.vim
+++ b/autoload/vital/__vital__/Color.vim
@@ -60,7 +60,6 @@ endfunction
 let s:RGB_HEX_RE = '\v^#(\x{3}(\x{3})?)$'
 let s:RGB_RE = '\v^rgb\((\d+\%?),\s*(\d+\%?),\s*(\d+\%?)\)$'
 let s:HSL_RE = '\v^hsl\((\d+),\s*(\d+)\%,\s*(\d+)\%\)$'
-let s:VIM_RGB_FILE = expand('$VIMRUNTIME/rgb.txt')
 function! s:parse(str) abort
   if type(a:str) !=# type('')
     throw 'vital: Color: parse(): invalid value type: ' . string(a:str)
@@ -89,20 +88,11 @@ function! s:parse(str) abort
     return s:hsl(h, s, l)
   endif
   " e.g. DarkGray
-  if exists('v:colornames')  " after patch 8.2.3562
-    let name = s:_normalize_color_name(a:str)
-    if has_key(v:colornames, name)
-      let m = matchlist(v:colornames[name], s:RGB_HEX_RE)
-      let [r, g, b] = [str2float('0x' . m[1][0:1]), str2float('0x' . m[1][2:3]), str2float('0x' . m[1][4:5])]
-      return s:rgb(r, g, b)
-    endif
-  elseif filereadable(s:VIM_RGB_FILE)
-    let color_map = s:_parse_rgb_file(s:VIM_RGB_FILE)
-    let name = s:_normalize_color_name(a:str)
-    if has_key(color_map, name)
-      let [r, g, b] = color_map[name]
-      return s:rgb(r, g, b)
-    endif
+  let name = s:_normalize_color_name(a:str)
+  if has_key(v:colornames, name)
+    let m = matchlist(v:colornames[name], s:RGB_HEX_RE)
+    let [r, g, b] = [str2float('0x' . m[1][0:1]), str2float('0x' . m[1][2:3]), str2float('0x' . m[1][4:5])]
+    return s:rgb(r, g, b)
   endif
   throw 'vital: Color: parse(): invalid format: ' . a:str
 endfunction
diff --git a/autoload/vital/__vital__/Data/List/Byte.vim b/autoload/vital/__vital__/Data/List/Byte.vim
index 3c05d7b32..ba847cbd9 100644
--- a/autoload/vital/__vital__/Data/List/Byte.vim
+++ b/autoload/vital/__vital__/Data/List/Byte.vim
@@ -27,19 +27,11 @@ function! s:validate(data) abort
 endfunction
 
 function! s:from_blob(blob) abort
-  if exists('*blob2list')  " add 8.2.3438
-    return blob2list(a:blob)
-  else
-    return s:List.new(len(a:blob), {i -> a:blob[i]})
-  endif
+  return blob2list(a:blob)
 endfunction
 
 function! s:to_blob(bytes) abort
-  if exists('*list2blob')  " add 8.2.3438
-    return list2blob(a:bytes)
-  else
-    return eval('0z' . s:to_hexstring(a:bytes))
-  endif
+  return list2blob(a:bytes)
 endfunction
 
 function! s:from_string(str) abort
diff --git a/autoload/vital/__vital__/Deprecated/Text/Sexp.vim b/autoload/vital/__vital__/Deprecated/Text/Sexp.vim
index 1b5daf1df..55d876e78 100644
--- a/autoload/vital/__vital__/Deprecated/Text/Sexp.vim
+++ b/autoload/vital/__vital__/Deprecated/Text/Sexp.vim
@@ -25,11 +25,8 @@ function! s:_vital_depends() abort
 endfunction
 
 " lua array index as 0 based.
-let s:_base = 0
-if has('patch-8.2.1066')
-  " fix lua array index as 1 based.
-  let s:_base = 1
-endif
+" after patch-8.2.1066, fix lua array index as 1 based.
+let s:_base = 1
 function! s:_index(idx) abort
   return printf('%d', s:_base + a:idx)
 endfunction
diff --git a/autoload/vital/__vital__/System/Filepath.vim b/autoload/vital/__vital__/System/Filepath.vim
index fa1254f9b..2e26a1a06 100644
--- a/autoload/vital/__vital__/System/Filepath.vim
+++ b/autoload/vital/__vital__/System/Filepath.vim
@@ -280,22 +280,9 @@ function! s:contains(path, base) abort
   return pathlist[: baselistlen - 1] ==# baselist
 endfunction
 
-if exists('+completeslash')
-  " completeslash bug in Windows and specific version range (Vim 8.1.1769 - Vim 8.2.1746)
-  function! s:expand(path) abort
-    let backup_completeslash = &completeslash
-    try
-      set completeslash&
-      return expand(a:path)
-    finally
-      let &completeslash = backup_completeslash
-    endtry
-  endfunction
-else
-  function! s:expand(path) abort
-    return expand(a:path)
-  endfunction
-endif
+function! s:expand(path) abort
+  return expand(a:path)
+endfunction
 
 let &cpo = s:save_cpo
 unlet s:save_cpo
diff --git a/doc/vital.txt b/doc/vital.txt
index f130f77f5..be4faa3bb 100644
--- a/doc/vital.txt
+++ b/doc/vital.txt
@@ -25,10 +25,10 @@ jQuery at the same time.
 If you are a Vim user who doesn't make Vim plugins, please ignore this page.
 If you are a Vim plugin author, please check this out.
 
-Modules in vital.vim basically support Vim 8.2 or later.
+Modules in vital.vim basically support Vim 9.0 or later.
 We guarantee that the following versions of Vim are supported:
-* The latest major version (9.0.*)
-* The previous major version (8.2.*)
+* The latest major version (9.1.*)
+* The previous major version (9.0.*)
 
 And some modules have stricter requirements and additional dependencies.
 Please read the docs of each module before using them.
diff --git a/test/Data/String/Interpolation.vimspec b/test/Data/String/Interpolation.vimspec
index 556e11094..a2ba589aa 100644
--- a/test/Data/String/Interpolation.vimspec
+++ b/test/Data/String/Interpolation.vimspec
@@ -51,11 +51,7 @@ Describe Data.String.Interpolation
     End
     It handle reassignment different type
       Assert Equals(g:I.interpolate('${a} ${b}', {'a': 1, 'b': '1'}), '1 1')
-      if !has('patch-8.2.2948')
-        Throws /Vim(let):E806:/ g:I.interpolate('${a} ${b}', {'a': 1, 'b': 1.0E-6})
-      else
-        Assert Equals(g:I.interpolate('${a} ${b}', {'a': 1, 'b': 1.0E-6}), '1 1.0e-6')
-      endif
+      Assert Equals(g:I.interpolate('${a} ${b}', {'a': 1, 'b': 1.0E-6}), '1 1.0e-6')
     End
     It doesn't raise Vim(let):E704: Funcref variable name must start with a capital
       Throws /Vim(let):E729:/ g:I.interpolate('${Funcref}', {'Funcref': function('InterpolationFunc')})
diff --git a/test/Deprecated/Text/Sexp.vim b/test/Deprecated/Text/Sexp.vim
index 6f7923925..30db45443 100644
--- a/test/Deprecated/Text/Sexp.vim
+++ b/test/Deprecated/Text/Sexp.vim
@@ -19,13 +19,7 @@ function! s:suite.parse()
   if !s:has_lua
     call s:assert.skip('Vital.Deprecated.Text.Sexp: any function call needs if_lua')
   endif
-  if has('patch-8.2.0775')
-    call s:assert.equals(
-          \ s:S.parse('(a b c)'),
-          \ [[{'label': 'identifier', 'col': 2, 'matched_text': 'a'}, {'label': 'whitespace', 'col': 3, 'matched_text': ' '}, {'label': 'identifier', 'col': 4, 'matched_text': 'b'}, {'label': 'whitespace', 'col': 5, 'matched_text': ' '}, {'label': 'identifier', 'col': 6, 'matched_text': 'c'}]])
-  else
-    call s:assert.equals(
-          \ s:S.parse('(a b c)'),
-          \ [[{'label': 'identifier', 'col': 2.0, 'matched_text': 'a'}, {'label': 'whitespace', 'col': 3.0, 'matched_text': ' '}, {'label': 'identifier', 'col': 4.0, 'matched_text': 'b'}, {'label': 'whitespace', 'col': 5.0, 'matched_text': ' '}, {'label': 'identifier', 'col': 6.0, 'matched_text': 'c'}]])
-  endif
+  call s:assert.equals(
+        \ s:S.parse('(a b c)'),
+        \ [[{'label': 'identifier', 'col': 2, 'matched_text': 'a'}, {'label': 'whitespace', 'col': 3, 'matched_text': ' '}, {'label': 'identifier', 'col': 4, 'matched_text': 'b'}, {'label': 'whitespace', 'col': 5, 'matched_text': ' '}, {'label': 'identifier', 'col': 6, 'matched_text': 'c'}]])
 endfunction