diff --git a/src/backtracer/backtrace/frame.cr b/src/backtracer/backtrace/frame.cr
index ad9ae5a..e99aed2 100644
--- a/src/backtracer/backtrace/frame.cr
+++ b/src/backtracer/backtrace/frame.cr
@@ -91,9 +91,9 @@ module Backtracer
     # Returns `true` if this frame originated from the app source code,
     # `false` otherwise.
     #
-    # See `Configuration#in_app_pattern`
+    # See `Configuration#app_dirs_pattern`
     def in_app? : Bool
-      !!(path.try(&.matches?(configuration.in_app_pattern)))
+      !!(relative_path.try(&.matches?(configuration.app_dirs_pattern)))
     end
 
     # Returns a tuple consisting of 3 elements - an array of context lines
diff --git a/src/backtracer/configuration.cr b/src/backtracer/configuration.cr
index 19fcd47..39184fe 100644
--- a/src/backtracer/configuration.cr
+++ b/src/backtracer/configuration.cr
@@ -53,7 +53,7 @@ module Backtracer
       /^(?<method>.+?)$/,
     }
 
-    # Used in `#in_app_pattern`.
+    # Path considered as "root" of your project.
     #
     # See `Frame#under_src_path?`
     property src_path : String? = {{ Process::INITIAL_PWD }}
@@ -63,12 +63,7 @@ module Backtracer
     # to set this to something like `/(src|engines)/`
     #
     # See `Frame#in_app?`
-    property app_dirs_pattern = /src/
-
-    # `Regex` pattern matched against `Backtrace::Frame#path`.
-    #
-    # See `Frame#in_app?`
-    property in_app_pattern : Regex { /^(#{src_path}\/)?(#{app_dirs_pattern})/ }
+    property app_dirs_pattern = /^src\//
 
     # Path pattern matching directories to be recognized as your app modules.
     # Defaults to standard Shards setup (`lib/shard-name/...`).