diff --git a/apps/NES/elpi/dune b/apps/NES/elpi/dune
index 45456e0cc..ff3aa20ed 100644
--- a/apps/NES/elpi/dune
+++ b/apps/NES/elpi/dune
@@ -9,7 +9,10 @@
   (glob_files *.elpi))
  (action
   (with-stdout-to %{target}
-   (echo ""))))
+   (progn
+     (echo "Require Import String.\nOpen Scope string_scope.\nLocal Definition _hash := \"\n")
+     (run coq_elpi_shafile %{deps})
+     (echo "\".\n")))))
 
 (install
  (files
diff --git a/apps/derive/elpi/dune b/apps/derive/elpi/dune
index e778456e0..1483b7fbc 100644
--- a/apps/derive/elpi/dune
+++ b/apps/derive/elpi/dune
@@ -9,7 +9,10 @@
   (glob_files *.elpi))
  (action
   (with-stdout-to %{target}
-   (echo ""))))
+   (progn
+     (echo "Require Import String.\nOpen Scope string_scope.\nLocal Definition _hash := \"\n")
+     (run coq_elpi_shafile %{deps})
+     (echo "\".\n")))))
 
 (install
  (files
diff --git a/apps/locker/elpi/dune b/apps/locker/elpi/dune
index ed682cc72..5f258ae21 100644
--- a/apps/locker/elpi/dune
+++ b/apps/locker/elpi/dune
@@ -9,7 +9,10 @@
   (glob_files *.elpi))
  (action
   (with-stdout-to %{target}
-   (echo ""))))
+   (progn
+     (echo "Require Import String.\nOpen Scope string_scope.\nLocal Definition _hash := \"\n")
+     (run coq_elpi_shafile %{deps})
+     (echo "\".\n")))))
 
 (install
  (files
diff --git a/apps/tc/elpi/dune b/apps/tc/elpi/dune
index 33b3f874c..5e9205d56 100644
--- a/apps/tc/elpi/dune
+++ b/apps/tc/elpi/dune
@@ -9,7 +9,10 @@
   (glob_files *.elpi))
  (action
   (with-stdout-to %{target}
-   (echo ""))))
+   (progn
+     (echo "Require Import String.\nOpen Scope string_scope.\nLocal Definition _hash := \"\n")
+     (run coq_elpi_shafile %{deps})
+     (echo "\".\n")))))
 
 (install
  (files
diff --git a/elpi/dune b/elpi/dune
index a39fb3b22..7c74d7fbc 100644
--- a/elpi/dune
+++ b/elpi/dune
@@ -8,7 +8,10 @@
   (glob_files *.elpi))
  (action
   (with-stdout-to %{target}
-   (echo ""))))
+   (progn
+     (echo "Require Import String.\nOpen Scope string_scope.\nLocal Definition _hash := \"\n")
+     (run coq_elpi_shafile %{deps})
+     (echo "\".\n")))))
 
 (install
  (files
diff --git a/etc/dune b/etc/dune
new file mode 100644
index 000000000..1b197edfc
--- /dev/null
+++ b/etc/dune
@@ -0,0 +1,5 @@
+(executable
+ (name shafile)
+ (public_name coq_elpi_shafile)
+ (modules shafile)
+ (package coq-elpi))
\ No newline at end of file
diff --git a/etc/shafile.ml b/etc/shafile.ml
new file mode 100644
index 000000000..27f66aae0
--- /dev/null
+++ b/etc/shafile.ml
@@ -0,0 +1,3 @@
+let () =
+  Sys.argv |> Array.iter (fun file ->
+    Printf.printf "%s: %s\n" file @@ Digest.to_hex @@ Digest.file file)
\ No newline at end of file