diff --git a/spec/ameba/cli/cmd_spec.cr b/spec/ameba/cli/cmd_spec.cr
index 624d1ad9..a412c194 100644
--- a/spec/ameba/cli/cmd_spec.cr
+++ b/spec/ameba/cli/cmd_spec.cr
@@ -20,14 +20,8 @@ module Ameba::Cli
 
       %w(-c --config).each do |f|
         it "accepts #{f} flag" do
-          c = Cli.parse_args [f, "shard.yml"]
-          c.config.should eq Path["shard.yml"]
-        end
-
-        it "raises when config file doesn't exist" do
-          expect_raises(ArgumentError, "Unable to find config file foo.yml") do
-            Cli.parse_args [f, "foo.yml"]
-          end
+          c = Cli.parse_args [f, "config.yml"]
+          c.config.should eq Path["config.yml"]
         end
       end
 
diff --git a/spec/ameba/config_spec.cr b/spec/ameba/config_spec.cr
index d738310f..6287de05 100644
--- a/spec/ameba/config_spec.cr
+++ b/spec/ameba/config_spec.cr
@@ -2,7 +2,7 @@ require "../spec_helper"
 
 module Ameba
   describe Config do
-    config_sample = "config/ameba.yml"
+    config_sample = "spec/ameba_fixture.yml"
 
     it "should have a list of available formatters" do
       Config::AVAILABLE_FORMATTERS.should_not be_nil
@@ -84,6 +84,12 @@ module Ameba
         config.formatter.should_not be_nil
       end
 
+      it "raises when custom config file doesn't exist" do
+        expect_raises(Exception, "Config file is invalid: Unable to find config file foo.yml") do
+          Config.load "foo.yml"
+        end
+      end
+
       it "loads default config" do
         config = Config.load
         config.should_not be_nil
diff --git a/spec/ameba_fixture.yml b/spec/ameba_fixture.yml
new file mode 100644
index 00000000..c5394b90
--- /dev/null
+++ b/spec/ameba_fixture.yml
@@ -0,0 +1,2 @@
+Lint/ComparisonToBoolean:
+  Enabled: true
diff --git a/src/ameba/cli/cmd.cr b/src/ameba/cli/cmd.cr
index 3b06b905..d8ce4a7e 100644
--- a/src/ameba/cli/cmd.cr
+++ b/src/ameba/cli/cmd.cr
@@ -77,8 +77,6 @@ module Ameba::Cli
 
       parser.on("-c", "--config PATH",
         "Specify a configuration file") do |path|
-        raise ArgumentError.new("Unable to find config file #{path}") if !File.exists?(path) && !opts.skip_reading_config?
-
         opts.config = Path[path] unless path.empty?
       end
 
diff --git a/src/ameba/config.cr b/src/ameba/config.cr
index 3d3a3c71..ad4f5dc6 100644
--- a/src/ameba/config.cr
+++ b/src/ameba/config.cr
@@ -120,7 +120,7 @@ class Ameba::Config
 
   protected def self.read_config(path = nil)
     if path
-      return File.exists?(path) ? File.read(path) : nil
+      return File.exists?(path) ? File.read(path) : raise("Unable to find config file #{path}")
     end
     each_config_path do |config_path|
       return File.read(config_path) if File.exists?(config_path)