diff --git a/spec/ameba/cli/cmd_spec.cr b/spec/ameba/cli/cmd_spec.cr
index c02068482..a5530baeb 100644
--- a/spec/ameba/cli/cmd_spec.cr
+++ b/spec/ameba/cli/cmd_spec.cr
@@ -156,6 +156,11 @@ module Ameba::Cli
         c.globs.should eq %w[source1.cr source2.cr]
       end
 
+      it "accepts single '-' argument as STDIN" do
+        c = Cli.parse_args %w[-]
+        c.stdin_filename.should eq "-"
+      end
+
       it "accepts one unknown arg as explain location if it has correct format" do
         c = Cli.parse_args %w[source.cr:3:22]
 
diff --git a/src/ameba/cli/cmd.cr b/src/ameba/cli/cmd.cr
index 3d6040d10..32d27772a 100644
--- a/src/ameba/cli/cmd.cr
+++ b/src/ameba/cli/cmd.cr
@@ -78,8 +78,11 @@ module Ameba::Cli
       parser.on("-r", "--rules", "Show all available rules") { opts.rules = true }
       parser.on("-s", "--silent", "Disable output") { opts.formatter = :silent }
       parser.unknown_args do |arr|
-        if arr.size == 1 && arr.first.matches?(/.+:\d+:\d+/)
+        case
+        when arr.size == 1 && arr.first.matches?(/.+:\d+:\d+/)
           configure_explain_opts(arr.first, opts)
+        when arr.size == 1 && arr.first == "-"
+          opts.stdin_filename = arr.first
         else
           opts.globs = arr unless arr.empty?
         end