diff --git a/setup.sh b/setup.sh
index 49245ec..4020627 100755
--- a/setup.sh
+++ b/setup.sh
@@ -284,18 +284,27 @@ fi
 header "Windows Cross-Compile"
 
 if $SETUP_WIN; then
-    win_pkgs="$(get_pkgs win)"
-    if [[ -n "$win_pkgs" ]]; then
-        install_pkgs "$win_pkgs" "Windows cross-compile"
-    fi
+    # Only touch apt / update-alternatives (which need sudo) when the toolchain is missing. If it is
+    # already installed, skip them so `./setup.sh --win` can run WITHOUT sudo — important because the
+    # daemon cross-compile that follows should run as the invoking user. Running the whole setup under
+    # sudo leaves root-owned build artifacts under external/dragonx, which then break `make clean` on
+    # a later non-sudo build (stale objects get relinked -> the mingw link failure recurs).
+    if has_cmd x86_64-w64-mingw32-g++-posix || has_cmd x86_64-w64-mingw32-g++; then
+        ok "Windows cross-compile toolchain already present — skipping apt install"
+    else
+        win_pkgs="$(get_pkgs win)"
+        if [[ -n "$win_pkgs" ]]; then
+            install_pkgs "$win_pkgs" "Windows cross-compile"
+        fi
 
-    # Set posix thread model if available
-    if has_cmd update-alternatives && [[ "$PKG" == "apt" ]]; then
-        if ! $CHECK_ONLY; then
-            sudo update-alternatives --set x86_64-w64-mingw32-gcc \
-                /usr/bin/x86_64-w64-mingw32-gcc-posix 2>/dev/null || true
-            sudo update-alternatives --set x86_64-w64-mingw32-g++ \
-                /usr/bin/x86_64-w64-mingw32-g++-posix 2>/dev/null || true
+        # Set posix thread model if available
+        if has_cmd update-alternatives && [[ "$PKG" == "apt" ]]; then
+            if ! $CHECK_ONLY; then
+                sudo update-alternatives --set x86_64-w64-mingw32-gcc \
+                    /usr/bin/x86_64-w64-mingw32-gcc-posix 2>/dev/null || true
+                sudo update-alternatives --set x86_64-w64-mingw32-g++ \
+                    /usr/bin/x86_64-w64-mingw32-g++-posix 2>/dev/null || true
+            fi
         fi
     fi