diff --git a/install.ps1 b/install.ps1
index ce742565..ce0c9662 100644
--- a/install.ps1
+++ b/install.ps1
@@ -8,7 +8,7 @@ param(
 
 $ErrorActionPreference = "Stop"
 $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-$defaultInstallSha256 = "3eac76733e9f27965ef62da4f3ef8e793b02af289d7a3317b1626c99a64ddcff"
+$defaultInstallSha256 = "d336ca66e88def775842bca2ed4fae67dabf1d3effcb18e84d057da78470459c"
 $maximumInstallerBytes = 2MB
 $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }
 $temporary = $null
diff --git a/install.py b/install.py
index 470c05bf..74b3f410 100644
--- a/install.py
+++ b/install.py
@@ -457,7 +457,7 @@ def _retroarch_cfg_dir(
 
 def _windows_retroarch_dirs() -> list[Path]:
     """Folders holding retroarch.exe where the installer and the archive put
-    it: C:\RetroArch-Win64 by default, C:\RetroArch for 32-bit builds."""
+    it: C:/RetroArch-Win64 by default, C:/RetroArch for 32-bit builds."""
     candidates = [Path("C:/RetroArch-Win64"), Path("C:/RetroArch")]
     for var in ("ProgramFiles", "ProgramFiles(x86)"):
         root = os.environ.get(var, "")
@@ -2170,6 +2170,7 @@ def _report_outcome(
     seconds: float = 0.0,
     declined: int = 0,
     assumed: set[Path] | None = None,
+    omitted_entries: list[dict] | None = None,
 ) -> None:
     """Close the run on what happened, and leave with a status that says so.
 
@@ -2218,11 +2219,29 @@ def _report_outcome(
           f"{_plural(up_to_date, 'file')} already up to date.")
     print(f"Location: {_locations(paths)}")
     if omitted:
-        print(f"{_plural(omitted, 'file')} are not in the collection yet "
-              "and were skipped.")
+        for line in _omission_lines(omitted, omitted_entries or []):
+            print(line)
     print("To check this later, run the same command with --check.")
 
 
+def _omission_lines(count: int, entries: list[dict]) -> list[str]:
+    """What was skipped, the files an emulator cannot start without first.
+
+    "395 file are not in the collection yet" named nothing and gave one
+    reason for all, while the manifest says which file and why.
+    """
+    one = count == 1
+    lines = [f"{_plural(count, 'file')} {'was' if one else 'were'} not installed: "
+             f"the collection does not hold {'it' if one else 'them'}, or its copy "
+             f"fails {'its' if one else 'their'} check."]
+    required = sorted({e["name"] for e in entries if e.get("required")})
+    if required:
+        shown = ", ".join(required[:10])
+        more = f" and {len(required) - 10} more" if len(required) > 10 else ""
+        lines.append(f"  Needed to start an emulator: {shown}{more}.")
+    return lines
+
+
 # Asked before, in an interactive run: past this size a download is worth a
 # second thought, and --system, --core or --region can make it smaller.
 CONFIRM_FROM_BYTES = 1024 * 1024 * 1024
@@ -2905,6 +2924,7 @@ def _install(args: argparse.Namespace, real_stdout) -> None:
     total_up_to_date = 0
     total_errors = 0
     total_omitted = 0
+    omitted_seen: list[dict] = []
     total_interrupted = False
     total_bytes = 0
     total_seconds = 0.0
@@ -3061,6 +3081,7 @@ def _install(args: argparse.Namespace, real_stdout) -> None:
                 f"entries omitted ({required_omitted} required; {reason_summary})."
             )
             total_omitted += len(omitted_files)
+            omitted_seen.extend(omitted_files)
 
         print("\nChecking existing files...")
         to_download, up_to_date, mismatched = check_local(
@@ -3184,6 +3205,7 @@ def _install(args: argparse.Namespace, real_stdout) -> None:
             seconds=total_seconds,
             declined=total_declined,
             assumed=assumed_dests,
+            omitted_entries=omitted_seen,
         )
 
 
diff --git a/install.sh b/install.sh
index 261683fe..4bd6d255 100755
--- a/install.sh
+++ b/install.sh
@@ -18,7 +18,7 @@ esac
 TEMP_INSTALLER=""
 TEMP_DIRECTORY=""
 DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-DEFAULT_INSTALL_SHA256="3eac76733e9f27965ef62da4f3ef8e793b02af289d7a3317b1626c99a64ddcff"
+DEFAULT_INSTALL_SHA256="d336ca66e88def775842bca2ed4fae67dabf1d3effcb18e84d057da78470459c"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {
diff --git a/tests/test_audit_regressions.py b/tests/test_audit_regressions.py
index 51019a37..cc75b8dd 100644
--- a/tests/test_audit_regressions.py
+++ b/tests/test_audit_regressions.py
@@ -3304,5 +3304,33 @@ class EveryReadmeNamesItsFolder(unittest.TestCase):
         self.assertNotIn("retroarch/system", lakka)
 
 
+
+class NoSourceWarnsWhenCompiled(unittest.TestCase):
+    """A docstring naming C:\\RetroArch-Win64 with one backslash compiled to
+    an invalid escape: a SyntaxWarning on every run of the installer."""
+
+    def test_every_script_compiles_clean(self):
+        import warnings
+
+        sources = [ROOT / "install.py", *sorted((ROOT / "scripts").rglob("*.py"))]
+        for path in sources:
+            with self.subTest(path=path.name), warnings.catch_warnings():
+                warnings.simplefilter("error", SyntaxWarning)
+                warnings.simplefilter("error", DeprecationWarning)
+                compile(path.read_text(encoding="utf-8"), str(path), "exec")
+
+
+class TheInstallerNamesWhatItSkipped(unittest.TestCase):
+    def test_count_agrees_and_required_files_are_named(self):
+        one = install._omission_lines(1, [{"name": "diabdat.mpq", "required": True}])
+        self.assertTrue(one[0].startswith("1 file was not installed"))
+        self.assertIn("diabdat.mpq", one[1])
+        many = install._omission_lines(
+            12, [{"name": f"f{i:02}", "required": True} for i in range(12)]
+        )
+        self.assertTrue(many[0].startswith("12 files were not installed"))
+        self.assertIn("and 2 more", many[1])
+
+
 if __name__ == "__main__":
     unittest.main()