diff --git a/fieldpattern.cpp b/fieldpattern.cpp
index af1fe124..0e304ae2 100644
--- a/fieldpattern.cpp
+++ b/fieldpattern.cpp
@@ -295,6 +295,7 @@ struct fpattern {
       exit(1);
       }
     build();
+    analyze();
     }
     
   fpattern(int p) {