diff --git a/feat-num.opam b/feat-num.opam
index 6e0c527d408549c8609418d6fc042d5f6f0c6553..15316c13301391df495c72032d36e3a1112283e5 100644
--- a/feat-num.opam
+++ b/feat-num.opam
@@ -13,7 +13,7 @@ build: [
 depends: [
   "ocaml" { >= "4.03" }
   "dune" { >= "1.4" }
-  "feat-core"
+  "feat-core" { = version }
   "num"
 ]
 synopsis: "Facilities for enumerating and sampling algebraic data types, using Num for big numbers"
diff --git a/feat.opam b/feat.opam
index fc3ff2e446b4239fa8d9ad6c821f49e12d708b26..3d020f2fec08604a1f9868643dd185bc5ed9161e 100644
--- a/feat.opam
+++ b/feat.opam
@@ -13,7 +13,7 @@ build: [
 depends: [
   "ocaml" { >= "4.03" }
   "dune" { >= "1.4" }
-  "feat-core"
+  "feat-core" { = version }
   "zarith"
 ]
 synopsis: "Facilities for enumerating and sampling algebraic data types, using Zarith for big numbers"