diff --git a/vim/prototool/ale_linters/proto/prototool.vim b/vim/prototool/ale_linters/proto/prototool.vim
index 6fc5c4848..893fc9f8c 100644
--- a/vim/prototool/ale_linters/proto/prototool.vim
+++ b/vim/prototool/ale_linters/proto/prototool.vim
@@ -27,6 +27,6 @@ call ale#linter#Define('proto', {
     \   'lint_file': 1,
     \   'output_stream': 'stdout',
     \   'executable': 'prototool',
-    \   'command_callback': 'ale_linters#proto#prototool#GetCommand',
+    \   'command': function('ale_linters#proto#prototool#GetCommand'),
     \   'callback': 'ale#handlers#unix#HandleAsError',
     \})
diff --git a/vim/prototool/ale_linters/proto/prototool_all.vim b/vim/prototool/ale_linters/proto/prototool_all.vim
index 0083d8051..e65884f6c 100644
--- a/vim/prototool/ale_linters/proto/prototool_all.vim
+++ b/vim/prototool/ale_linters/proto/prototool_all.vim
@@ -9,6 +9,6 @@ call ale#linter#Define('proto', {
     \   'lint_file': 1,
     \   'output_stream': 'stdout',
     \   'executable': 'prototool',
-    \   'command_callback': 'ale_linters#proto#prototool_all#GetCommand',
+    \   'command': function('ale_linters#proto#prototool_all#GetCommand'),
     \   'callback': 'ale#handlers#unix#HandleAsError',
     \})
diff --git a/vim/prototool/ale_linters/proto/prototool_compile.vim b/vim/prototool/ale_linters/proto/prototool_compile.vim
index 4f64474ee..cedc2da01 100644
--- a/vim/prototool/ale_linters/proto/prototool_compile.vim
+++ b/vim/prototool/ale_linters/proto/prototool_compile.vim
@@ -9,6 +9,6 @@ call ale#linter#Define('proto', {
     \   'lint_file': 1,
     \   'output_stream': 'stdout',
     \   'executable': 'prototool',
-    \   'command_callback': 'ale_linters#proto#prototool_compile#GetCommand',
+    \   'command': function('ale_linters#proto#prototool_compile#GetCommand'),
     \   'callback': 'ale#handlers#unix#HandleAsError',
     \})
diff --git a/vim/prototool/ale_linters/proto/prototool_lint.vim b/vim/prototool/ale_linters/proto/prototool_lint.vim
index 63d050a79..b74a12225 100644
--- a/vim/prototool/ale_linters/proto/prototool_lint.vim
+++ b/vim/prototool/ale_linters/proto/prototool_lint.vim
@@ -9,6 +9,6 @@ call ale#linter#Define('proto', {
     \   'lint_file': 1,
     \   'output_stream': 'stdout',
     \   'executable': 'prototool',
-    \   'command_callback': 'ale_linters#proto#prototool_lint#GetCommand',
+    \   'command': function('ale_linters#proto#prototool_lint#GetCommand'),
     \   'callback': 'ale#handlers#unix#HandleAsError',
     \})