diff --git a/pom.xml b/pom.xml
@@ -88,6 +88,12 @@
      <version>0.9.29-1</version>
      <optional>true</optional>
    </dependency>
  </dependencies>
  <build>
    <plugins>
@@ -110,6 +116,8 @@
          </usedDependencies>
          <ignoredDependencies>
            <ignoredDependency>com.github.jnr:jffi</ignoredDependency>
          </ignoredDependencies>
        </configuration>
      </plugin>

diff --git a/src/main/java/org/lmdbjava/Cursor.java b/src/main/java/org/lmdbjava/Cursor.java
@@ -162,6 +162,7 @@ public boolean get(final T key, final T data, final SeekOp op) {
    checkRc(rc);
    kv.keyOut();
    kv.valOut();
    return true;
  }

@@ -192,6 +193,7 @@ public boolean get(final T key, final GetOp op) {
    checkRc(rc);
    kv.keyOut();
    kv.valOut();
    return true;
  }

@@ -266,6 +268,8 @@ public boolean put(final T key, final T val, final PutFlags... op) {
      return false;
    }
    checkRc(rc);
    return true;
  }

@@ -304,6 +308,8 @@ public void putMultiple(final T key, final T val, final int elements,
    final int rc = LIB.mdb_cursor_put(ptrCursor, txn.kv().pointerKey(),
                                      dataPtr, mask);
    checkRc(rc);
  }

  /**
@@ -362,6 +368,7 @@ public T reserve(final T key, final int size, final PutFlags... op) {
    checkRc(LIB.mdb_cursor_put(ptrCursor, kv.pointerKey(), kv.pointerVal(),
                               flags));
    kv.valOut();
    return val();
  }


diff --git a/src/main/java/org/lmdbjava/Dbi.java b/src/main/java/org/lmdbjava/Dbi.java
@@ -171,6 +171,8 @@ public boolean delete(final Txn<T> txn, final T key, final T val) {
      return false;
    }
    checkRc(rc);
    return true;
  }

@@ -239,6 +241,7 @@ public T get(final Txn<T> txn, final T key) {
      return null;
    }
    checkRc(rc);
    return txn.kv().valOut(); // marked as out in LMDB C docs
  }

@@ -386,6 +389,8 @@ public boolean put(final Txn<T> txn, final T key, final T val,
      return false;
    }
    checkRc(rc);
    return true;
  }

@@ -421,6 +426,7 @@ public T reserve(final Txn<T> txn, final T key, final int size,
    checkRc(LIB.mdb_put(txn.pointer(), ptr, txn.kv().pointerKey(), txn.kv()
                        .pointerVal(), flags));
    txn.kv().valOut(); // marked as in,out in LMDB C docs
    return txn.val();
  }


diff --git a/src/main/java/org/lmdbjava/ReferenceUtil.java b/src/main/java/org/lmdbjava/ReferenceUtil.java
@@ -0,0 +1,55 @@
diff --git a/src/test/java/org/lmdbjava/GarbageCollectionTest.java b/src/test/java/org/lmdbjava/GarbageCollectionTest.java
@@ -0,0 +1,111 @@