diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index a0947af853b..0ba29605c02 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -299,8 +299,7 @@ jobs:
           target/release/rustpython -m test -j 1 --slowest --fail-env-changed -v -x ${{ env.PLATFORM_INDEPENDENT_TESTS }} ${{ env.WINDOWS_SKIPS }}
         timeout-minutes: 45
 
-      - if: runner.os != 'Windows'
-        name: check that --install-pip succeeds
+      - name: check that --install-pip succeeds
         run: |
           mkdir site-packages
           target/release/rustpython --install-pip ensurepip --user
@@ -309,11 +308,10 @@ jobs:
         run: |
           target/release/rustpython -m ensurepip
           target/release/rustpython -c "import pip"
-      - if: runner.os != 'Windows'
-        name: Check if pip inside venv is functional
+      - name: Check if pip inside venv is functional
         run: |
           target/release/rustpython -m venv testvenv
-          testvenv/bin/rustpython -m pip install wheel
+          testvenv/bin/rustpython -m pip install flask
       - name: Check whats_left is not broken
         run: python -I whats_left.py
 
diff --git a/crates/vm/src/stdlib/ctypes.rs b/crates/vm/src/stdlib/ctypes.rs
index 9b922230431..83143aa4a0c 100644
--- a/crates/vm/src/stdlib/ctypes.rs
+++ b/crates/vm/src/stdlib/ctypes.rs
@@ -579,7 +579,9 @@ pub(crate) mod _ctypes {
         vm: &VirtualMachine,
     ) -> PyResult<usize> {
         // Default mode: RTLD_NOW | RTLD_LOCAL, always force RTLD_NOW
-        let mode = load_flags.unwrap_or(libc::RTLD_NOW | libc::RTLD_LOCAL) | libc::RTLD_NOW;
+        let mode = load_flags
+            .map(|m| m | libc::RTLD_NOW)
+            .unwrap_or(libc::RTLD_NOW | libc::RTLD_LOCAL);
 
         match name {
             Some(name) => {
@@ -641,6 +643,13 @@ pub(crate) mod _ctypes {
         name: crate::builtins::PyStrRef,
         vm: &VirtualMachine,
     ) -> PyResult<usize> {
+        // Validate the handle exists in the library cache before calling dlsym
+        let cache = library::libcache().read();
+        if cache.get_lib(handle).is_none() {
+            return Err(vm.new_os_error("invalid library handle"));
+        }
+        drop(cache);
+
         let symbol_name = std::ffi::CString::new(name.as_str())
             .map_err(|_| vm.new_value_error("symbol name contains null byte"))?;
 
diff --git a/crates/vm/src/stdlib/ctypes/library.rs b/crates/vm/src/stdlib/ctypes/library.rs
index 7512ce29d8a..cbab950632c 100644
--- a/crates/vm/src/stdlib/ctypes/library.rs
+++ b/crates/vm/src/stdlib/ctypes/library.rs
@@ -6,7 +6,9 @@ use std::ffi::OsStr;
 use std::fmt;
 
 #[cfg(unix)]
-use libloading::os::unix::Library as UnixLibrary;
+use libloading::os::unix::Library as OsLibrary;
+#[cfg(windows)]
+use libloading::os::windows::Library as OsLibrary;
 
 pub struct SharedLibrary {
     pub(crate) lib: PyMutex<Option<Library>>,
@@ -33,7 +35,7 @@ impl SharedLibrary {
     ) -> Result<SharedLibrary, libloading::Error> {
         Ok(SharedLibrary {
             lib: PyMutex::new(Some(unsafe {
-                UnixLibrary::open(Some(name.as_ref()), mode)?.into()
+                OsLibrary::open(Some(name.as_ref()), mode)?.into()
             })),
         })
     }
@@ -42,19 +44,39 @@ impl SharedLibrary {
     #[cfg(unix)]
     pub fn from_raw_handle(handle: *mut libc::c_void) -> SharedLibrary {
         SharedLibrary {
-            lib: PyMutex::new(Some(unsafe { UnixLibrary::from_raw(handle).into() })),
+            lib: PyMutex::new(Some(unsafe { OsLibrary::from_raw(handle).into() })),
         }
     }
 
     /// Get the underlying OS handle (HMODULE on Windows, dlopen handle on Unix)
+    #[cfg(unix)]
     pub fn get_pointer(&self) -> usize {
-        let lib_lock = self.lib.lock();
-        if let Some(l) = &*lib_lock {
-            // libloading::Library internally stores the OS handle directly
-            // On Windows: HMODULE (*mut c_void)
-            // On Unix: *mut c_void from dlopen
-            // We use transmute_copy to read the handle without consuming the Library
-            unsafe { std::mem::transmute_copy::<Library, usize>(l) }
+        let mut lib_lock = self.lib.lock();
+        if let Some(lib) = lib_lock.take() {
+            // Use official libloading API: convert to platform-specific type,
+            // extract raw handle, then reconstruct
+            let unix_lib: OsLibrary = lib.into();
+            let handle = unix_lib.into_raw();
+            // Reconstruct the library from the raw handle and put it back
+            *lib_lock = Some(unsafe { OsLibrary::from_raw(handle) }.into());
+            handle as usize
+        } else {
+            0
+        }
+    }
+
+    /// Get the underlying OS handle (HMODULE on Windows, dlopen handle on Unix)
+    #[cfg(windows)]
+    pub fn get_pointer(&self) -> usize {
+        let mut lib_lock = self.lib.lock();
+        if let Some(lib) = lib_lock.take() {
+            // Use official libloading API: convert to platform-specific type,
+            // extract raw handle, then reconstruct
+            let win_lib: OsLibrary = lib.into();
+            let handle = win_lib.into_raw();
+            // Reconstruct the library from the raw handle and put it back
+            *lib_lock = Some(unsafe { OsLibrary::from_raw(handle) }.into());
+            handle as usize
         } else {
             0
         }