diff --git a/install.ps1 b/install.ps1
index 3799ebb3..f5b961f7 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 = "aec72e43585459efb0fd49d2eafb49b0e898b9ddc0f9ca2f44c7636080e21425"
+$defaultInstallSha256 = "b6a3729bd7b1e954f691b915355b81b0f310de2eb21c5a34cbc5637b5cf06f07"
 $maximumInstallerBytes = 2MB
 $installerExit = 0
 $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }
diff --git a/install.py b/install.py
index 7d1bff91..826cffed 100644
--- a/install.py
+++ b/install.py
@@ -2403,6 +2403,10 @@ def _download_one(
         except _Corrupt:
             if verbose:
                 print(f"    {reason} on attempt {attempt}", file=sys.stderr)
+            # Closed before the delete: Windows refuses to remove a file
+            # still open (WinError 32), and the error ended the run.
+            if partial is not None:
+                partial.close()
             if tmp_path is not None and tmp_path.exists():
                 tmp_path.unlink()
             delay = 0.0
@@ -2416,6 +2420,8 @@ def _download_one(
             if tmp_path is not None and partial is None and tmp_path.exists():
                 tmp_path.unlink()
             if exc.code == 416 and tmp_path is not None and tmp_path.exists():
+                if partial is not None:
+                    partial.close()
                 tmp_path.unlink()  # the partial copy no longer fits the file
             delay = _retry_delay(attempt, exc.headers.get("Retry-After") if exc.headers else None)
 
diff --git a/install.sh b/install.sh
index b90fe852..b722041a 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="aec72e43585459efb0fd49d2eafb49b0e898b9ddc0f9ca2f44c7636080e21425"
+DEFAULT_INSTALL_SHA256="b6a3729bd7b1e954f691b915355b81b0f310de2eb21c5a34cbc5637b5cf06f07"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {
diff --git a/tests/test_install.py b/tests/test_install.py
index 000b18c8..700e766c 100644
--- a/tests/test_install.py
+++ b/tests/test_install.py
@@ -2672,5 +2672,18 @@ class ThePagesQuoteTheBootstrapsOwnWords(unittest.TestCase):
             self.assertIn(quoted, " ".join(text.split()))
 
 
+
+class APartialIsClosedBeforeItIsDeleted(unittest.TestCase):
+    """Windows refuses to delete an open file: a resumed partial copy whose
+    hash no longer matched was unlinked with its handle still open, and the
+    PermissionError ended the run."""
+
+    def test_the_source_closes_first(self):
+        source = (REPO_ROOT / "install.py").read_text(encoding="utf-8")
+        branch = source[source.index("        except _Corrupt:"):]
+        branch = branch[:branch.index("delay = 0.0")]
+        self.assertLess(branch.index("partial.close()"), branch.index("tmp_path.unlink()"))
+
+
 if __name__ == "__main__":
     unittest.main()