diff --git a/nix/frama-c.nix b/nix/frama-c.nix
index 347ca1f1225f16a076bd463f305311197f51af10..34d0802ce288a8f63d33b0a58d16a5fca606b806 100644
--- a/nix/frama-c.nix
+++ b/nix/frama-c.nix
@@ -84,6 +84,8 @@ stdenvNoCC.mkDerivation rec {
 
   preConfigure = ''
     autoconf
+    patchShebangs src/plugins/value/gen-api.sh
+    chmod +x src/plugins/value/gen-api.sh
   '';
 
   # Do not use default parallel building, but allow 2 cores for Frama-C build