diff --git a/src/bin/dune b/src/bin/dune
index 60874931e..f0219a5f6 100644
--- a/src/bin/dune
+++ b/src/bin/dune
@@ -31,7 +31,7 @@
   (modules runligo)
   (package ligo)
   (preprocess
-    (pps ppx_let)
+    (pps ppx_let bisect_ppx --conditional)
   )
   (flags (:standard -open Simple_utils))
 )
diff --git a/src/passes/1-parser/cameligo/dune b/src/passes/1-parser/cameligo/dune
index f68e85661..5604f5065 100644
--- a/src/passes/1-parser/cameligo/dune
+++ b/src/passes/1-parser/cameligo/dune
@@ -27,6 +27,8 @@
    parser_cameligo)
   (modules
     LexerMain)
+  (preprocess
+    (pps bisect_ppx --conditional))
   (flags (:standard -open Parser_shared -open Parser_cameligo)))
 
 (executable
@@ -36,4 +38,6 @@
   (modules
     ParserAPI
     ParserMain)
+  (preprocess
+    (pps bisect_ppx --conditional))
   (flags (:standard -open Simple_utils -open Parser_shared -open Parser_cameligo)))
diff --git a/src/passes/1-parser/pascaligo/dune b/src/passes/1-parser/pascaligo/dune
index a5bcdc6b7..28fee7d04 100644
--- a/src/passes/1-parser/pascaligo/dune
+++ b/src/passes/1-parser/pascaligo/dune
@@ -17,8 +17,7 @@
    tezos-utils
  )
  (preprocess
-   (pps bisect_ppx --conditional)
- )
+   (pps bisect_ppx --conditional))
  (flags (:standard  -open Parser_shared -open Simple_utils))
 )
 
@@ -30,18 +29,25 @@
      tezos-utils
      parser_pascaligo)
   (modules
-     LexerMain)
-  (flags (:standard -open Parser_shared -open Parser_pascaligo)))
+    LexerMain)
+  (preprocess
+    (pps bisect_ppx --conditional))
+  (flags (:standard -open Parser_shared -open Parser_pascaligo))
+)
 
 (executable
   (name ParserMain)
   (libraries
      parser_pascaligo)
   (modules ParserMain)
+  (preprocess
+    (pps bisect_ppx --conditional))
   (flags (:standard -open Simple_utils -open Parser_shared -open Parser_pascaligo)))
 
 (executable
   (name Unlexer)
+  (preprocess
+    (pps bisect_ppx --conditional))
   (modules Unlexer))
 
 ;; Les deux directives (rule) qui suivent sont pour le dev local.
diff --git a/src/passes/1-parser/reasonligo/dune b/src/passes/1-parser/reasonligo/dune
index e98678262..fc7b1d15e 100644
--- a/src/passes/1-parser/reasonligo/dune
+++ b/src/passes/1-parser/reasonligo/dune
@@ -28,9 +28,13 @@
   (name LexerMain)
   (libraries
    parser_reasonligo)
-  (modules
+  (modules 
     LexerMain)
-  (flags (:standard -open Parser_shared -open Parser_reasonligo)))
+  (preprocess
+   (pps bisect_ppx --conditional)
+  )
+  (flags (:standard -open Parser_shared -open Parser_reasonligo))
+)
 
 (executable
   (name ParserMain)
@@ -40,4 +44,7 @@
   (modules
     ParserAPI
     ParserMain)
+  (preprocess
+   (pps bisect_ppx --conditional)
+  )
   (flags (:standard -open Simple_utils -open Parser_cameligo -open Parser_shared -open Parser_reasonligo)))