diff --git a/README.md b/README.md
index bcde889fad..81b43716d4 100644
--- a/README.md
+++ b/README.md
@@ -305,7 +305,11 @@ amtool template render --template.glob='/foo/bar/*.tmpl' --template.text='{{ tem
 
 ### Configuration
 
-`amtool` allows a configuration file to specify some options for convenience. The default configuration file paths are `$HOME/.config/amtool/config.yml` or `/etc/amtool/config.yml`
+`amtool` allows a configuration file to specify some options for convenience. The default configuration file paths are, in order of precedence:
+
+1. The environment variable `AMTOOL_CONFIG_FILE`, if set.
+2. `$HOME/.config/amtool/config.yml`
+3. `/etc/amtool/config.yml`
 
 An example configuration file might look like the following:
 
diff --git a/cli/root.go b/cli/root.go
index 572f173428..47726db6b9 100644
--- a/cli/root.go
+++ b/cli/root.go
@@ -44,9 +44,8 @@ var (
 	httpConfigFile  string
 	versionCheck    bool
 	featureFlags    string
-
-	configFiles = []string{os.ExpandEnv("$HOME/.config/amtool/config.yml"), "/etc/amtool/config.yml"}
-	legacyFlags = map[string]string{"comment_required": "require-comment"}
+	configFiles     = []string{os.Getenv("AMTOOL_CONFIG_FILE"), os.ExpandEnv("$HOME/.config/amtool/config.yml"), "/etc/amtool/config.yml"}
+	legacyFlags     = map[string]string{"comment_required": "require-comment"}
 )
 
 func initMatchersCompat(_ *kingpin.ParseContext) error {
@@ -191,9 +190,10 @@ const (
 	helpRoot = `View and modify the current Alertmanager state.
 
 Config File:
-The alertmanager tool will read a config file in YAML format from one of two
-default config locations: $HOME/.config/amtool/config.yml or
-/etc/amtool/config.yml
+The alertmanager tool will read a config file in YAML format from one of the following locations, in order of precedence:
+	1. The environment variable AMTOOL_CONFIG_FILE, if set.
+	2. $HOME/.config/amtool/config.yml
+	3. /etc/amtool/config.yml
 
 All flags can be given in the config file, but the following are the suited for
 static configuration: