diff --git a/openssl-sys/src/lib.rs b/openssl-sys/src/lib.rs
index aa3a0df5..829f6bc1 100644
--- a/openssl-sys/src/lib.rs
+++ b/openssl-sys/src/lib.rs
@@ -1090,6 +1090,8 @@ extern "C" {
     pub fn sk_pop_free(st: *mut _STACK, free: Option<unsafe extern "C" fn (*mut c_void)>);
     pub fn sk_pop(st: *mut _STACK) -> *mut c_char;
 
+    pub fn GENERAL_NAME_free(name: *mut GENERAL_NAME);
+
     pub fn SSLeay() -> c_long;
     pub fn SSLeay_version(key: c_int) -> *const c_char;
 }
diff --git a/openssl/src/x509/mod.rs b/openssl/src/x509/mod.rs
index 4943f7a9..fb6c2aaa 100644
--- a/openssl/src/x509/mod.rs
+++ b/openssl/src/x509/mod.rs
@@ -408,7 +408,7 @@ impl<'a> X509Ref<'a> {
             }
 
             Some(GeneralNames {
-                stack: stack as *const _,
+                stack: stack as *mut _,
                 m: PhantomData,
             })
         }
@@ -735,12 +735,23 @@ make_validation_error!(X509_V_OK,
     X509ApplicationVerification = X509_V_ERR_APPLICATION_VERIFICATION,
 );
 
+// FIXME remove lifetime param for 0.9
 /// A collection of OpenSSL `GENERAL_NAME`s.
 pub struct GeneralNames<'a> {
-    stack: *const ffi::stack_st_GENERAL_NAME,
+    stack: *mut ffi::stack_st_GENERAL_NAME,
     m: PhantomData<&'a ()>,
 }
 
+impl<'a> Drop for GeneralNames<'a> {
+    fn drop(&mut self) {
+        unsafe {
+            let free: unsafe extern "C" fn(*mut ffi::GENERAL_NAME) = ffi::GENERAL_NAME_free;
+            let free: unsafe extern "C" fn(*mut c_void) = mem::transmute(free);
+            ffi::sk_pop_free(&mut (*self.stack).stack, Some(free));
+        }
+    }
+}
+
 impl<'a> GeneralNames<'a> {
     /// Returns the number of `GeneralName`s in this structure.
     pub fn len(&self) -> usize {