gistfile1.diff

diff --git a/vm/capi/gc.cpp b/vm/capi/gc.cpp
index c6231e4..71c17a0 100644
--- a/vm/capi/gc.cpp
+++ b/vm/capi/gc.cpp
@@ -55,6 +55,11 @@ extern "C" {
    * to be in the heap.
    */
   void rb_gc_mark_maybe(VALUE ptr) {
-    rb_gc_mark(ptr);
+    NativeMethodEnvironment* env = NativeMethodEnvironment::get();
+    Handle* handle = Handle::from(ptr);
+
+    if(capi::Handle::valid_handle_p(env->state(), handle)) {
+      rb_gc_mark(ptr);
+    }
   }
 }
diff --git a/vm/capi/handle.cpp b/vm/capi/handle.cpp
index dff1ea2..32e1f17 100644
--- a/vm/capi/handle.cpp
+++ b/vm/capi/handle.cpp
@@ -5,6 +5,17 @@
 
 namespace rubinius {
   namespace capi {
+
+    bool Handle::valid_handle_p(STATE, Handle* handle) {
+      Handles* handles = state->shared.global_handles();
+
+      for(Handles::Iterator i(*handles); i.more(); i.advance()) {
+        if(i.current() == handle) return true;
+      }
+
+      return false;
+    }
+
     void Handle::free_data() {
       if(as_.cache_data) {
         switch(type_) {
diff --git a/vm/capi/handle.hpp b/vm/capi/handle.hpp
index 06ab6e2..4f28c8e 100644
--- a/vm/capi/handle.hpp
+++ b/vm/capi/handle.hpp
@@ -63,6 +63,8 @@ namespace rubinius {
         as_.cache_data = 0;
       }
 
+      static bool valid_handle_p(STATE, Handle* handle);
+
       ~Handle();
 
       void flush(NativeMethodEnvironment* env) {