diff --git a/colibri2.opam b/colibri2.opam
index 39732a7e83a6e32b22e51acf8d8f3bc25d6e9bf9..8e0cd52faebe403aad42066c3e7427cf0dc3b610 100644
--- a/colibri2.opam
+++ b/colibri2.opam
@@ -9,7 +9,7 @@ authors: [
   "Guillaume Bury"
   "Stéphane Graham-Lengrand"
 ]
-license: "LGPL-3.0-only"
+license: "LGPL-2.1"
 homepage: "https://colibri.frama-c.com"
 bug-reports: "https://git.frama-c.com/pub/colibrics/issues"
 depends: [
diff --git a/colibrics.opam b/colibrics.opam
index 8038ec2e155cd0f102adc45f844912b542a12732..c66fe447a815e9acc520a926c75578ec8e0bdb7f 100644
--- a/colibrics.opam
+++ b/colibrics.opam
@@ -4,6 +4,7 @@ synopsis: "A CP solver proved in Why3"
 description: "The core of Colibrics is formally proved using Why3."
 maintainer: ["François Bobot"]
 authors: ["François Bobot"]
+license: "LGPL-2.1"
 homepage: "https://colibri.frama-c.com"
 bug-reports: "https://git.frama-c.com/pub/colibrics/issues"
 depends: [
diff --git a/colibrilib.opam b/colibrilib.opam
index 8353d1fc0ec81be86d3d40fd90b322733fae46e8..0df2c5f153c881466c57414f0f36c3d2e1059dbb 100644
--- a/colibrilib.opam
+++ b/colibrilib.opam
@@ -4,6 +4,7 @@ synopsis: "A library of domains and propagators proved in Why3"
 description: "Interval, and union of interval domains defined formally"
 maintainer: ["François Bobot"]
 authors: ["François Bobot"]
+license: "LGPL-2.1"
 homepage: "https://colibri.frama-c.com"
 bug-reports: "https://git.frama-c.com/pub/colibrics/issues"
 depends: [
diff --git a/dune-project b/dune-project
index 92393c50797ce84f644dc1fe8df8b6790a764618..3d7d9925e558fb9e7b2435eb4e68cd877c0ad9d7 100644
--- a/dune-project
+++ b/dune-project
@@ -8,6 +8,7 @@
 (source (uri "git+https://git.frama-c.com/pub/colibrics.git"))
 (homepage "https://colibri.frama-c.com")
 (bug_reports "https://git.frama-c.com/pub/colibrics/issues")
+(license "LGPL-2.1")
 
 (name colibri2)
 (package
@@ -50,7 +51,6 @@
 (package (name colibri2)
          (authors "François Bobot" "Bruno Marre" "Guillaume Bury" "Stéphane Graham-Lengrand")
          (maintainers "François Bobot")
-         (license LGPL-3.0-only)
          (synopsis "A CP solver for smtlib")
          (description "A reimplementation of COLIBRI in OCaml")
          (depends