diff --git a/multidb/pinning.py b/multidb/pinning.py
index aa529c2..8f554e9 100644
--- a/multidb/pinning.py
+++ b/multidb/pinning.py
@@ -34,7 +34,7 @@ def unpin_this_thread():
 
 
 class UsePrimaryDB(object):
-    """A contextmanager/decorator to use the master database."""
+    """A contextmanager/decorator to use the primary database."""
     def __call__(self, func):
         @wraps(func)
         def decorator(*args, **kw):
@@ -43,11 +43,12 @@ def decorator(*args, **kw):
         return decorator
 
     def __enter__(self):
-        _locals.old = this_thread_is_pinned()
+        _locals.old = getattr(_locals, 'old', [])
+        _locals.old.append(this_thread_is_pinned())
         pin_this_thread()
 
     def __exit__(self, type, value, tb):
-        if not _locals.old:
+        if not _locals.old.pop():
             unpin_this_thread()
 
 
diff --git a/multidb/tests.py b/multidb/tests.py
index 125cff4..136e63a 100644
--- a/multidb/tests.py
+++ b/multidb/tests.py
@@ -202,6 +202,22 @@ def check():
         check()
         assert not this_thread_is_pinned()
 
+    def test_decorator_nested(self):
+        @use_primary_db
+        def check_inner():
+            assert this_thread_is_pinned()
+
+        @use_primary_db
+        def check_outer():
+            assert this_thread_is_pinned()
+            check_inner()
+            assert this_thread_is_pinned()
+
+        unpin_this_thread()
+        assert not this_thread_is_pinned()
+        check_outer()
+        assert not this_thread_is_pinned()
+
     def test_decorator_resets(self):
         @use_primary_db
         def check():
@@ -211,6 +227,22 @@ def check():
         check()
         assert this_thread_is_pinned()
 
+    def test_decorator_resets_nested(self):
+        @use_primary_db
+        def check_inner():
+            assert this_thread_is_pinned()
+
+        @use_primary_db
+        def check_outer():
+            assert this_thread_is_pinned()
+            check_inner()
+            assert this_thread_is_pinned()
+
+        pin_this_thread()
+        assert this_thread_is_pinned()
+        check_outer()
+        assert this_thread_is_pinned()
+
     def test_context_manager(self):
         unpin_this_thread()
         assert not this_thread_is_pinned()
@@ -218,6 +250,16 @@ def test_context_manager(self):
             assert this_thread_is_pinned()
         assert not this_thread_is_pinned()
 
+    def test_context_manager_nested(self):
+        unpin_this_thread()
+        assert not this_thread_is_pinned()
+        with use_primary_db:
+            assert this_thread_is_pinned()
+            with use_primary_db:
+                assert this_thread_is_pinned()
+            assert this_thread_is_pinned()
+        assert not this_thread_is_pinned()
+
     def test_context_manager_resets(self):
         pin_this_thread()
         assert this_thread_is_pinned()
@@ -225,6 +267,16 @@ def test_context_manager_resets(self):
             assert this_thread_is_pinned()
         assert this_thread_is_pinned()
 
+    def test_context_manager_resets_nested(self):
+        pin_this_thread()
+        assert this_thread_is_pinned()
+        with use_primary_db:
+            assert this_thread_is_pinned()
+            with use_primary_db:
+                assert this_thread_is_pinned()
+            assert this_thread_is_pinned()
+        assert this_thread_is_pinned()
+
     def test_context_manager_exception(self):
         unpin_this_thread()
         assert not this_thread_is_pinned()