diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 9c917e1f5a..31ed27ce87 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -49,17 +49,17 @@ jobs:
             skip-test: false
             skip-doc: true
           - os: ubuntu-latest
-            ocaml-compiler: "ocaml-variants.5.3.0+trunk"
+            ocaml-compiler: "ocaml-variants.5.3.0~alpha1"
             skip-effects: false
             skip-test: false
             skip-doc: false
           - os: macos-latest
-            ocaml-compiler: "ocaml-variants.5.3.0+trunk"
+            ocaml-compiler: "ocaml-variants.5.3.0~alpha1"
             skip-effects: true
             skip-test: false
             skip-doc: true
           - os: windows-latest
-            ocaml-compiler: "ocaml-variants.5.3.0+trunk"
+            ocaml-compiler: "ocaml-variants.5.3.0~alpha1"
             skip-effects: false
             skip-test: false
             skip-doc: true
@@ -92,12 +92,10 @@ jobs:
       - run: opam install conf-pkg-config
         if: runner.os == 'Windows'
 
-      - run: opam pin add ppxlib git+https://github.com/NathanReb/ppxlib.git#trunk-support-503 --no-action
-        if: ${{ matrix.ocaml-compiler == 'ocaml-variants.5.3.0+trunk' }}
-      - run: opam pin add base        git+https://github.com/hhugo/base.git#trunk-support-503 --no-action
-        if: ${{ matrix.ocaml-compiler == 'ocaml-variants.5.3.0+trunk' }}
+      - run: opam pin add ppxlib --dev --no-action
+        if: ${{ matrix.ocaml-compiler == 'ocaml-variants.5.3.0~alpha1' }}
       - run: opam pin add ppxlib_jane git+https://github.com/hhugo/ppxlib_jane.git#trunk-support-503 --no-action
-        if: ${{ matrix.ocaml-compiler == 'ocaml-variants.5.3.0+trunk' }}
+        if: ${{ matrix.ocaml-compiler == 'ocaml-variants.5.3.0~alpha1' }}
 
       - run: opam pin add ./ --no-action
 
diff --git a/compiler/lib/magic_number.ml b/compiler/lib/magic_number.ml
index 26c9d53dea..e476410004 100644
--- a/compiler/lib/magic_number.ml
+++ b/compiler/lib/magic_number.ml
@@ -79,7 +79,7 @@ let v =
   | 5 :: 02 :: _ -> 34
   | 5 :: 03 :: _ -> 35
   | _ ->
-      if Ocaml_version.compare current [ 4; 08 ] < 0
+      if Ocaml_version.compare current [ 4; 8 ] < 0
       then failwith "OCaml version unsupported. Upgrade to OCaml 4.08 or newer."
       else (
         assert (Ocaml_version.compare current [ 5; 4 ] >= 0);
diff --git a/ppx/ppx_js/tests/ppx.mlt b/ppx/ppx_js/tests/ppx.mlt
index e1c1510135..02d7850ebf 100644
--- a/ppx/ppx_js/tests/ppx.mlt
+++ b/ppx/ppx_js/tests/ppx.mlt
@@ -102,7 +102,7 @@ fun (obj : int) -> obj##m
 [%%expect
 {|
 Line _, characters 19-22:
-Error: This expression has type int but an expression was expected of type
+Error: The value obj has type int but an expression was expected of type
          < .. > Js_of_ocaml.Js.t
 |}]
 
@@ -122,7 +122,7 @@ fun (obj : < m : float Js.prop > Js.t) -> obj##m
 [%%expect
 {|
 Line _, characters 42-48:
-Error: This expression has type
+Error: The method call x#m has type
          float Js_of_ocaml.Js.prop =
            < get : float; set : float -> unit > Js_of_ocaml.Js.gen_prop
        but an expression was expected of type 'res Js_of_ocaml.Js.meth
@@ -144,7 +144,7 @@ fun (obj : < m : int -> int Js.meth > Js.t) -> obj##m + 1
 [%%expect
 {|
 Line _, characters 47-53:
-Error: This expression has type int -> int Js_of_ocaml.Js.meth
+Error: The method call x#m has type int -> int Js_of_ocaml.Js.meth
        but an expression was expected of type 'res Js_of_ocaml.Js.meth
 |}]
 
@@ -154,7 +154,7 @@ fun (obj : < m : int Js.meth > Js.t) -> obj##m 1
 [%%expect
 {|
 Line _, characters 40-46:
-Error: This expression has type int Js_of_ocaml.Js.meth
+Error: The method call x#m has type int Js_of_ocaml.Js.meth
        but an expression was expected of type int -> 'res Js_of_ocaml.Js.meth
 |}]
 
@@ -189,7 +189,7 @@ fun (obj : int) -> obj##.p
 [%%expect
 {|
 Line _, characters 19-22:
-Error: This expression has type int but an expression was expected of type
+Error: The value obj has type int but an expression was expected of type
          < .. > Js_of_ocaml.Js.t
 |}]
 
@@ -209,7 +209,7 @@ fun (obj : < p : float Js.writeonly_prop > Js.t) -> obj##.p + 1
 [%%expect
 {|
 Line _, characters 58-59:
-Error: This expression has type
+Error: The method call x#p has type
          float Js_of_ocaml.Js.writeonly_prop =
            < set : float -> unit > Js_of_ocaml.Js.gen_prop
        but an expression was expected of type
@@ -235,7 +235,7 @@ fun (obj : int) -> obj##.p := 2
 [%%expect
 {|
 Line _, characters 19-22:
-Error: This expression has type int but an expression was expected of type
+Error: The value obj has type int but an expression was expected of type
          < .. > Js_of_ocaml.Js.t
 |}]
 
@@ -255,7 +255,7 @@ fun (obj : < p : float Js.readonly_prop > Js.t) -> obj##.p := 1
 [%%expect
 {|
 Line _, characters 51-58:
-Error: This expression has type
+Error: The method call x#p has type
          float Js_of_ocaml.Js.readonly_prop =
            < get : float > Js_of_ocaml.Js.gen_prop
        but an expression was expected of type
@@ -269,7 +269,7 @@ fun (obj : < p : float Js.prop > Js.t) -> obj##.p := 1
 [%%expect
 {|
 Line _, characters 42-49:
-Error: This expression has type
+Error: The method call x#p has type
          float Js_of_ocaml.Js.prop =
            < get : float; set : float -> unit > Js_of_ocaml.Js.gen_prop
        but an expression was expected of type
diff --git a/runtime/array.js b/runtime/array.js
index fb027359d7..8672f15660 100644
--- a/runtime/array.js
+++ b/runtime/array.js
@@ -27,6 +27,17 @@ function caml_array_sub(a, i, len) {
   return a2;
 }
 
+//Provides: caml_floatarray_sub mutable
+//Version: >= 5.3
+function caml_floatarray_sub(a, i, len) {
+  var a2 = new Array(len + 1);
+  a2[0] = 0;
+  for (var i2 = 1, i1 = i + 1; i2 <= len; i2++, i1++) {
+    a2[i2] = a[i1];
+  }
+  return a2;
+}
+
 //Provides: caml_array_append mutable
 function caml_array_append(a1, a2) {
   var l1 = a1.length,
@@ -41,6 +52,21 @@ function caml_array_append(a1, a2) {
   return a;
 }
 
+//Provides: caml_floatarray_append mutable
+//Version: >= 5.3
+function caml_floatarray_append(a1, a2) {
+  var l1 = a1.length,
+    l2 = a2.length;
+  var l = l1 + l2 - 1;
+  var a = new Array(l);
+  a[0] = 0;
+  var i = 1,
+    j = 1;
+  for (; i < l1; i++) a[i] = a1[i];
+  for (; i < l; i++, j++) a[i] = a2[j];
+  return a;
+}
+
 //Provides: caml_array_concat mutable
 function caml_array_concat(l) {
   var a = [0];
@@ -96,6 +122,15 @@ function caml_array_fill(array, ofs, len, v) {
   return 0;
 }
 
+//Provides: caml_floatarray_fill
+//Version: >= 5.3
+function caml_floatarray_fill(array, ofs, len, v) {
+  for (var i = 0; i < len; i++) {
+    array[ofs + i + 1] = v;
+  }
+  return 0;
+}
+
 //Provides: caml_check_bound (mutable, const)
 //Requires: caml_array_bound_error
 function caml_check_bound(array, index) {
@@ -133,6 +168,7 @@ function caml_array_create_float(len) {
 }
 //Provides: caml_floatarray_create const (const)
 //Requires: caml_array_bound_error
+//Version: >= 5.3
 function caml_floatarray_create(len) {
   if (len < 0) caml_array_bound_error();
   var len = (len + 1) | 0;
@@ -141,3 +177,10 @@ function caml_floatarray_create(len) {
   for (var i = 1; i < len; i++) b[i] = 0;
   return b;
 }
+
+//Provides: caml_floatarray_make const (const)
+//Requires: caml_array_make
+//Version: >= 5.3
+function caml_floatarray_make(len,init) {
+  return caml_array_make(len,init);
+}