diff --git a/vendors/Preproc/Preproc.mll b/vendors/Preproc/Preproc.mll
index 37c5c89f8..7359918f7 100644
--- a/vendors/Preproc/Preproc.mll
+++ b/vendors/Preproc/Preproc.mll
@@ -4,7 +4,7 @@
 (* START OF HEADER *)
 
 module Region = Simple_utils.Region
-(*module Pos = Simple_utils.Pos*)
+module Pos = Simple_utils.Pos
 
 let sprintf = Printf.sprintf
 
diff --git a/vendors/Preproc/dune b/vendors/Preproc/dune
index d50457a90..17fec5492 100644
--- a/vendors/Preproc/dune
+++ b/vendors/Preproc/dune
@@ -1,23 +1,37 @@
-(ocamllex E_Lexer Preproc)
+(ocamllex
+   E_Lexer Preproc)
 
 (menhir
   (modules E_Parser))
 
 (library
-  (name PreProc)
+  (name Preproc)
   (public_name ligo.preproc)
   (libraries
      getopt
      simple-utils)
   (wrapped false)
-  (modules E_Parser E_Lexer E_AST Preproc))
+  (modules EvalOpt E_Parser E_Lexer E_AST Preproc)
+  (preprocess
+    (pps bisect_ppx --conditional)))
 
-(test
-  (modules ProcMain)
-  (libraries PreProc)
-  (name ProcMain))
+(executable
+  (name PreprocMain)
+  (modules PreprocMain)
+  (libraries Preproc)
+  (preprocess
+    (pps bisect_ppx --conditional)))
 
-(test
-  (modules E_Main)
-  (libraries PreProc)
-  (name E_Main))
+(executable
+  (name E_LexerMain)
+  (modules E_LexerMain)
+  (libraries Preproc)
+  (preprocess
+    (pps bisect_ppx --conditional)))
+
+(executable
+  (name E_ParserMain)
+  (modules E_ParserMain)
+  (libraries Preproc)
+  (preprocess
+    (pps bisect_ppx --conditional)))