diff --git a/l7-filter-userspace/trunk/l7-classify.cpp b/l7-filter-userspace/trunk/l7-classify.cpp
index 8b5b77e..1c80d4d 100644
--- a/l7-filter-userspace/trunk/l7-classify.cpp
+++ b/l7-filter-userspace/trunk/l7-classify.cpp
@@ -59,6 +59,7 @@ l7_pattern::l7_pattern(string name, string pattern_string, int eflags,
     cerr << "error compiling " << name << " -- " << pattern_string << endl;
     exit(1);
   }
+  free(preprocessed);
 }