diff --git a/build-inso-installer.sh b/build-inso-installer.sh
index d3d46da090..2f2ba416f3 100755
--- a/build-inso-installer.sh
+++ b/build-inso-installer.sh
@@ -4,12 +4,17 @@
 set -e
 
 VERSION=$(jq .version ./packages/insomnia-inso/package.json -rj)
-BINARIES_DIR=packages/insomnia-inso/binaries
-OUT_DIR=packages/insomnia-inso/artifacts
 INSTALLER_DIR=packages/insomnia-inso/installer
 
-mkdir -p $OUT_DIR
+mkdir -p packages/insomnia-inso/artifacts
+
+# NSIS's File directive resolves relative paths against the .nsi script's own directory,
+# not the process's working directory — pass absolute, native Windows-style paths instead
+# (cygpath converts this shell's POSIX-style path to the C:\... form makensis.exe needs).
+ROOT_WIN=$(cygpath -w "$(pwd)")
+BINARIES_DIR="$ROOT_WIN\\packages\\insomnia-inso\\binaries"
+OUT_DIR="$ROOT_WIN\\packages\\insomnia-inso\\artifacts"
 
 echo "Building inso-installer.exe for version $VERSION..."
-makensis -DVERSION=$VERSION -DBINARIES_DIR=$BINARIES_DIR -DOUT_DIR=$OUT_DIR $INSTALLER_DIR/inso-installer.nsi
-echo "Done. See $OUT_DIR/inso-installer.exe"
+makensis -DVERSION=$VERSION -DBINARIES_DIR="$BINARIES_DIR" -DOUT_DIR="$OUT_DIR" $INSTALLER_DIR/inso-installer.nsi
+echo "Done. See $OUT_DIR\\inso-installer.exe"