diff --git a/build-common.sh b/build-common.sh
index a29f39a..1f9dd59 100644
--- a/build-common.sh
+++ b/build-common.sh
@@ -91,8 +91,11 @@ cleanup_site_packages() {
     find "$sp_dir" -name "*.pyi" -delete 2>/dev/null || true
     rm -rf "$sp_dir"/{pip,setuptools,pkg_resources,_distutils_hack}* 2>/dev/null || true
 
-    # Trim numpy if present
-    for mod in polynomial linalg ma lib distutils f2py typing _pyinstaller; do
+    # Trim numpy if present.
+    # Keep only modules that numpy/__init__.py does NOT import unconditionally —
+    # lib, linalg, ma, polynomial, fft, ctypeslib, matrixlib are all required for
+    # `import numpy` to succeed, so they MUST stay.
+    for mod in distutils f2py typing _pyinstaller; do
         rm -rf "$sp_dir/numpy/$mod" 2>/dev/null || true
     done