Index: pyyaml/trunk/lib/yaml/resolver.py
===================================================================
--- pyyaml/trunk/lib/yaml/resolver.py	(revision 59)
+++ pyyaml/trunk/lib/yaml/resolver.py	(revision 132)
@@ -57,5 +57,5 @@
 
     def resolve_scalar(self, path, node):
-        if node.tag is None:
+        if node.tag is None and node.implicit:
             node.tag = self.detect_scalar(node.value)
         if node.tag is None or node.tag == u'!':