diff --git a/src/fileiter.cpp b/src/fileiter.cpp
index 780a12f1..5f65127f 100644
--- a/src/fileiter.cpp
+++ b/src/fileiter.cpp
@@ -267,14 +267,15 @@ void mapfile::lock(pointer* node)const
            read_size = std::fread(*node + sizeof(int), _size % buf_size, 1, hfile); 
         else
            read_size = std::fread(*node + sizeof(int), buf_size, 1, hfile);
-#ifndef BOOST_NO_EXCEPTIONS 
         if((read_size == 0) || (std::ferror(hfile)))
         { 
+#ifndef BOOST_NO_EXCEPTIONS 
+           unlock(node);
            throw std::runtime_error("Unable to read file."); 
-        } 
 #else 
-        BOOST_REGEX_NOEH_ASSERT((0 == std::ferror(hfile)) && (read_size != 0)); 
+           BOOST_REGEX_NOEH_ASSERT((0 == std::ferror(hfile)) && (read_size != 0)); 
 #endif 
+        } 
       }
       else
       {