diff --git a/lib/default.nix b/lib/default.nix
index dfa69f1..92d2399 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -1,4 +1,9 @@
-{pkgs, ...}: {
+{
+  pkgs,
+  lib ? pkgs.lib,
+  self ? "",
+  ...
+}: {
   mkTest = {
     type ? "unit",
     name,
@@ -7,13 +12,15 @@
     actual ? null,
     actualDrv ? null,
     pos ? null,
-  }: {
+  }: let
+    fileRelative = lib.removePrefix ((toString self) + "/") pos.file;
+  in {
     inherit type name description expected actual;
     actualDrv = actualDrv.drvPath or "";
     pos =
       if pos == null
       then ""
-      else "${pos.file}:${toString pos.line}:${toString pos.column}";
+      else "${fileRelative}:${toString pos.line}:${toString pos.column}";
   };
   mkSuite = name: tests: {
     inherit name tests;
diff --git a/lib/flakeModule.nix b/lib/flakeModule.nix
index 12d900f..0d09608 100644
--- a/lib/flakeModule.nix
+++ b/lib/flakeModule.nix
@@ -1,6 +1,7 @@
 {
   flake-parts-lib,
   lib,
+  self,
   ...
 }: let
   inherit (lib) mkOption types;
@@ -11,7 +12,7 @@ in {
       pkgs,
       ...
     }: let
-      nixtests-lib = import ./. {inherit pkgs;};
+      nixtests-lib = import ./. {inherit pkgs self;};
     in {
       options.testSuites = mkOption {
         type = types.attrsOf (types.listOf types.attrs);