diff --git a/ale_linters/sh/shell.vim b/ale_linters/sh/shell.vim
index 8f5ca3ae..cf5e4e6c 100644
--- a/ale_linters/sh/shell.vim
+++ b/ale_linters/sh/shell.vim
@@ -17,18 +17,10 @@ if !exists('g:ale_sh_shell_default_shell')
 endif
 
 function! ale_linters#sh#shell#GetExecutable(buffer) abort
-    let l:banglines = getbufline(a:buffer, 1)
+    let l:shell_type = ale#handlers#sh#GetShellType(a:buffer)
 
-    " Take the shell executable from the hashbang, if we can.
-    if len(l:banglines) == 1 && l:banglines[0] =~# '^#!'
-        " Remove options like -e, etc.
-        let l:line = substitute(l:banglines[0], '--\?[a-zA-Z0-9]\+', '', 'g')
-
-        for l:possible_shell in ['bash', 'tcsh', 'csh', 'zsh', 'sh']
-            if l:line =~# l:possible_shell . '\s*$'
-                return l:possible_shell
-            endif
-        endfor
+    if !empty(l:shell_type)
+        return l:shell_type
     endif
 
     return ale#Var(a:buffer, 'sh_shell_default_shell')
diff --git a/ale_linters/sh/shellcheck.vim b/ale_linters/sh/shellcheck.vim
index 5353683d..3a2d33f2 100644
--- a/ale_linters/sh/shellcheck.vim
+++ b/ale_linters/sh/shellcheck.vim
@@ -19,25 +19,35 @@ function! ale_linters#sh#shellcheck#GetExecutable(buffer) abort
     return ale#Var(a:buffer, 'sh_shellcheck_executable')
 endfunction
 
-function! s:GetDialectArgument() abort
-    if exists('b:is_bash') && b:is_bash
-        return '-s bash'
-    elseif exists('b:is_sh') && b:is_sh
-        return '-s sh'
-    elseif exists('b:is_kornshell') && b:is_kornshell
-        return '-s ksh'
+function! ale_linters#sh#shellcheck#GetDialectArgument(buffer) abort
+    let l:shell_type = ale#handlers#sh#GetShellType(a:buffer)
+
+    if !empty(l:shell_type)
+        return l:shell_type
+    endif
+
+    " If there's no hashbang, try using Vim's buffer variables.
+    if get(b:, 'is_bash')
+        return 'bash'
+    elseif get(b:, 'is_sh')
+        return 'sh'
+    elseif get(b:, 'is_kornshell')
+        return 'ksh'
     endif
 
     return ''
 endfunction
 
 function! ale_linters#sh#shellcheck#GetCommand(buffer) abort
+    let l:options = ale#Var(a:buffer, 'sh_shellcheck_options')
     let l:exclude_option = ale#Var(a:buffer, 'sh_shellcheck_exclusions')
+    let l:dialect = ale_linters#sh#shellcheck#GetDialectArgument(a:buffer)
 
     return ale_linters#sh#shellcheck#GetExecutable(a:buffer)
-    \   . ' ' . ale#Var(a:buffer, 'sh_shellcheck_options')
-    \   . ' ' . (!empty(l:exclude_option) ? '-e ' . l:exclude_option : '')
-    \   . ' ' . s:GetDialectArgument() . ' -f gcc -'
+    \   . (!empty(l:options) ? ' ' . l:options : '')
+    \   . (!empty(l:exclude_option) ? ' -e ' . l:exclude_option : '')
+    \   . (!empty(l:dialect) ? ' -s ' . l:dialect : '')
+    \   . ' -f gcc -'
 endfunction
 
 call ale#linter#Define('sh', {
diff --git a/autoload/ale/handlers/sh.vim b/autoload/ale/handlers/sh.vim
new file mode 100644
index 00000000..894879ee
--- /dev/null
+++ b/autoload/ale/handlers/sh.vim
@@ -0,0 +1,20 @@
+" Author: w0rp <devw0rp@gmail.com>
+
+" Get the shell type for a buffer, based on the hashbang line.
+function! ale#handlers#sh#GetShellType(buffer) abort
+    let l:bang_line = get(getbufline(a:buffer, 1), 0, '')
+
+    " Take the shell executable from the hashbang, if we can.
+    if l:bang_line[:1] is# '#!'
+        " Remove options like -e, etc.
+        let l:command = substitute(l:bang_line, ' --\?[a-zA-Z0-9]\+', '', 'g')
+
+        for l:possible_shell in ['bash', 'tcsh', 'csh', 'zsh', 'sh']
+            if l:command =~# l:possible_shell . '\s*$'
+                return l:possible_shell
+            endif
+        endfor
+    endif
+
+    return ''
+endfunction
diff --git a/test/command_callback/test_shellcheck_command_callback.vader b/test/command_callback/test_shellcheck_command_callback.vader
new file mode 100644
index 00000000..0d8fef66
--- /dev/null
+++ b/test/command_callback/test_shellcheck_command_callback.vader
@@ -0,0 +1,47 @@
+Before:
+  Save g:ale_sh_shellcheck_exclusions
+  Save g:ale_sh_shellcheck_executable
+  Save g:ale_sh_shellcheck_options
+
+  unlet! g:ale_sh_shellcheck_exclusions
+  unlet! g:ale_sh_shellcheck_executable
+  unlet! g:ale_sh_shellcheck_options
+
+  runtime ale_linters/sh/shellcheck.vim
+
+After:
+  Restore
+
+  unlet! b:ale_sh_shellcheck_exclusions
+  unlet! b:ale_sh_shellcheck_executable
+  unlet! b:ale_sh_shellcheck_options
+  unlet! b:is_bash
+
+  call ale#linter#Reset()
+
+Execute(The default shellcheck command should be correct):
+  AssertEqual
+  \ 'shellcheck -f gcc -',
+  \ ale_linters#sh#shellcheck#GetCommand(bufnr(''))
+
+Execute(The shellcheck command should accept options):
+  let b:ale_sh_shellcheck_options = '--foobar'
+
+  AssertEqual
+  \ 'shellcheck --foobar -f gcc -',
+  \ ale_linters#sh#shellcheck#GetCommand(bufnr(''))
+
+Execute(The shellcheck command should accept options and exclusions):
+  let b:ale_sh_shellcheck_options = '--foobar'
+  let b:ale_sh_shellcheck_exclusions = 'foo,bar'
+
+  AssertEqual
+  \ 'shellcheck --foobar -e foo,bar -f gcc -',
+  \ ale_linters#sh#shellcheck#GetCommand(bufnr(''))
+
+Execute(The shellcheck command should include the dialect):
+  let b:is_bash = 1
+
+  AssertEqual
+  \ 'shellcheck -s bash -f gcc -',
+  \ ale_linters#sh#shellcheck#GetCommand(bufnr(''))
diff --git a/test/test_shell_detection.vader b/test/test_shell_detection.vader
new file mode 100644
index 00000000..37cf43ce
--- /dev/null
+++ b/test/test_shell_detection.vader
@@ -0,0 +1,83 @@
+Before:
+  runtime ale_linters/sh/shell.vim
+  runtime ale_linters/sh/shellcheck.vim
+
+After:
+  call ale#linter#Reset()
+
+  unlet! b:is_bash
+  unlet! b:is_sh
+  unlet! b:is_kornshell
+
+Given(A file with a Bash hashbang):
+  #!/bin/bash
+
+Execute(/bin/bash should be detected appropriately):
+  AssertEqual 'bash', ale#handlers#sh#GetShellType(bufnr(''))
+  AssertEqual 'bash', ale_linters#sh#shell#GetExecutable(bufnr(''))
+  AssertEqual 'bash', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))
+
+Given(A file with /bin/sh):
+  #!/usr/bin/env sh -eu --foobar
+
+Execute(/bin/sh should be detected appropriately):
+  AssertEqual 'sh', ale#handlers#sh#GetShellType(bufnr(''))
+  AssertEqual 'sh', ale_linters#sh#shell#GetExecutable(bufnr(''))
+  AssertEqual 'sh', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))
+
+Given(A file with bash as an argument to env):
+  #!/usr/bin/env bash
+
+Execute(/usr/bin/env bash should be detected appropriately):
+  AssertEqual 'bash', ale#handlers#sh#GetShellType(bufnr(''))
+  AssertEqual 'bash', ale_linters#sh#shell#GetExecutable(bufnr(''))
+  AssertEqual 'bash', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))
+
+Given(A file with a tcsh hash bang and arguments):
+  #!/usr/bin/env tcsh -eu --foobar
+
+Execute(tcsh should be detected appropriately):
+  AssertEqual 'tcsh', ale#handlers#sh#GetShellType(bufnr(''))
+  AssertEqual 'tcsh', ale_linters#sh#shell#GetExecutable(bufnr(''))
+  AssertEqual 'tcsh', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))
+
+Given(A file with a zsh hash bang and arguments):
+  #!/usr/bin/env zsh -eu --foobar
+
+Execute(zsh should be detected appropriately):
+  AssertEqual 'zsh', ale#handlers#sh#GetShellType(bufnr(''))
+  AssertEqual 'zsh', ale_linters#sh#shell#GetExecutable(bufnr(''))
+  AssertEqual 'zsh', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))
+
+Given(A file with a csh hash bang and arguments):
+  #!/usr/bin/env csh -eu --foobar
+
+Execute(zsh should be detected appropriately):
+  AssertEqual 'csh', ale#handlers#sh#GetShellType(bufnr(''))
+  AssertEqual 'csh', ale_linters#sh#shell#GetExecutable(bufnr(''))
+  AssertEqual 'csh', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))
+
+Given(A file with a sh hash bang and arguments):
+  #!/usr/bin/env sh -eu --foobar
+
+Execute(sh should be detected appropriately):
+  AssertEqual 'sh', ale#handlers#sh#GetShellType(bufnr(''))
+  AssertEqual 'sh', ale_linters#sh#shell#GetExecutable(bufnr(''))
+  AssertEqual 'sh', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))
+
+Given(A file without a hashbang):
+
+Execute(The bash dialect should be used for shellcheck if b:is_bash is 1):
+  let b:is_bash = 1
+
+  AssertEqual 'bash', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))
+
+Execute(The sh dialect should be used for shellcheck if b:is_sh is 1):
+  let b:is_sh = 1
+
+  AssertEqual 'sh', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))
+
+Execute(The ksh dialect should be used for shellcheck if b:is_kornshell is 1):
+  let b:is_kornshell = 1
+
+  AssertEqual 'ksh', ale_linters#sh#shellcheck#GetDialectArgument(bufnr(''))