diff --git a/reason.json b/reason.json
index c4becebcd..b439be88e 100644
--- a/reason.json
+++ b/reason.json
@@ -8,7 +8,7 @@
     "url": "https://github.com/reasonml/reason.git"
   },
   "dependencies": {
-    "ocaml": " >= 4.2.0 < 4.15.0",
+    "ocaml": ">= 4.2.0 < 5.1.0",
     "@opam/fix": "*",
     "@opam/ocamlfind": "*",
     "@opam/menhir": " >= 20180523.0.0",
@@ -22,6 +22,13 @@
     "ocaml": "~4.12.0"
   },
   "esy": {
-    "build": [["dune", "build", "-p", "reason"]]
+    "build": [
+      [
+        "dune",
+        "build",
+        "-p",
+        "reason"
+      ]
+    ]
   }
 }
diff --git a/reason.opam b/reason.opam
index a208c3789..fb3770113 100644
--- a/reason.opam
+++ b/reason.opam
@@ -11,8 +11,8 @@ build: [
   ["dune" "build" "-p" name "-j" jobs]
 ]
 depends: [
-  "ocaml"         {>= "4.03" & < "4.15"}
-  "dune"          {>= "1.4"}
+  "ocaml"         {>= "4.03" & < "5.1"}
+  "dune"          {>= "2.3"}
   "ocamlfind"     {build}
   "menhir"        {>= "20180523"}
   "merlin-extend" {>= "0.6"}
diff --git a/rtop.json b/rtop.json
index f9c74c1e4..388f2cbd1 100644
--- a/rtop.json
+++ b/rtop.json
@@ -13,7 +13,7 @@
     "@opam/dune": "2.9.3",
     "@opam/reason": "^3.8.0",
     "@opam/utop": " >= 1.17.0",
-    "ocaml": ">= 4.2.0 < 4.14.0"
+    "ocaml": ">= 4.2.0 < 5.1.0"
   },
   "devDependencies": {
     "@opam/merlin": "*",
@@ -21,7 +21,12 @@
   },
   "esy": {
     "build": [
-      [ "dune", "build", "-p", "rtop"]
+      [
+        "dune",
+        "build",
+        "-p",
+        "rtop"
+      ]
     ]
   }
 }
diff --git a/rtop.opam b/rtop.opam
index 87a07f034..e7c83b706 100644
--- a/rtop.opam
+++ b/rtop.opam
@@ -11,8 +11,8 @@ build: [
   ["dune" "build" "-p" name "-j" jobs]
 ]
 depends: [
-  "ocaml"  {>= "4.02" & < "4.15"}
-  "dune"   {>= "1.4"}
+  "ocaml"  {>= "4.03" & < "5.1"}
+  "dune"   {>= "2.3"}
   "reason" {=version}
   "utop"   {>= "2.0"}
 ]