diff --git a/compiler/core/lam_compile.ml b/compiler/core/lam_compile.ml
index 680bce50a7..87a25bfe2a 100644
--- a/compiler/core/lam_compile.ml
+++ b/compiler/core/lam_compile.ml
@@ -814,14 +814,29 @@ let compile output_prefix =
       | _ -> false
     in
     let clause_is_not_typeof (tag, _) = tag_is_not_typeof tag in
-    let clause_is_object_typeof = function
-      | Ast_untagged_variants.Untagged ObjectType, _ -> true
-      | _ -> false
-    in
     let switch ?default ?declaration e clauses =
       let not_typeof_clauses, typeof_clauses =
         List.partition clause_is_not_typeof clauses
       in
+      let has_object_typeof =
+        List.exists
+          (function
+            | Ast_untagged_variants.Untagged ObjectType, _ -> true
+            | _ -> false)
+          typeof_clauses
+      in
+      let has_array_case =
+        List.exists
+          (function
+            | Ast_untagged_variants.Untagged (InstanceType Array), _ -> true
+            | _ -> false)
+          not_typeof_clauses
+      in
+      (* When there's an ObjectType typeof case, null and arrays can
+         incorrectly match it (typeof null === typeof [] === "object").
+         Guard against them when they should fall through to default. *)
+      let needs_null_guard = has_object_typeof && has_null_case in
+      let needs_array_guard = has_object_typeof && not has_array_case in
       let rec build_if_chain remaining_clauses =
         match remaining_clauses with
         | ( Ast_untagged_variants.Untagged (InstanceType instance_type),
@@ -831,17 +846,21 @@ let compile output_prefix =
             (E.emit_check (IsInstanceOf (instance_type, Expr e)))
             switch_body
             ~else_:[build_if_chain rest]
-        | _ ->
+        | _ -> (
           let typeof_switch () =
             S.string_switch ?default ?declaration (E.typeof e) typeof_clauses
           in
-          if has_null_case && List.exists clause_is_object_typeof typeof_clauses
-          then
-            match default with
-            | Some default_body ->
-              S.if_ (E.is_null e) default_body ~else_:[typeof_switch ()]
-            | None -> typeof_switch ()
-          else typeof_switch ()
+          let guard =
+            match (needs_null_guard, needs_array_guard) with
+            | true, true -> Some (E.or_ (E.is_null e) (E.is_array e))
+            | true, false -> Some (E.is_null e)
+            | false, true -> Some (E.is_array e)
+            | false, false -> None
+          in
+          match (guard, default) with
+          | Some guard, Some default_body ->
+            S.if_ guard default_body ~else_:[typeof_switch ()]
+          | _ -> typeof_switch ())
       in
       build_if_chain not_typeof_clauses
     in
diff --git a/tests/tests/src/js_json_test.mjs b/tests/tests/src/js_json_test.mjs
index c69a9fd6f3..8ff5ed4fa0 100644
--- a/tests/tests/src/js_json_test.mjs
+++ b/tests/tests/src/js_json_test.mjs
@@ -367,7 +367,7 @@ Mocha.describe("Js_json_test", () => {
     Test_utils.eq("File \"js_json_test.res\", line 314, characters 7-14", Js_json.decodeArray({}), undefined);
     Test_utils.eq("File \"js_json_test.res\", line 315, characters 7-14", Js_json.decodeArray(1.23), undefined);
   });
-  Mocha.test("JSON Array/Object switch falls through to wildcard on null", () => {
+  Mocha.test("JSON Array/Object switch falls through to wildcard on null and array", () => {
     let classifyArrayOrObject = json => {
       if (Array.isArray(json)) {
         return json.length;
@@ -386,25 +386,42 @@ Mocha.describe("Js_json_test", () => {
     Test_utils.eq("File \"js_json_test.res\", line 328, characters 7-14", classifyArrayOrObject(null), undefined);
     Test_utils.eq("File \"js_json_test.res\", line 329, characters 7-14", classifyArrayOrObject([1]), 1);
     Test_utils.eq("File \"js_json_test.res\", line 330, characters 7-14", classifyArrayOrObject({}), 0);
+    let classifyObjectOnly = json => {
+      if (json === null || Array.isArray(json)) {
+        return "default";
+      }
+      switch (typeof json) {
+        case "string" :
+          return "String";
+        case "object" :
+          return "Object";
+        default:
+          return "default";
+      }
+    };
+    Test_utils.eq("File \"js_json_test.res\", line 340, characters 7-14", classifyObjectOnly(null), "default");
+    Test_utils.eq("File \"js_json_test.res\", line 341, characters 7-14", classifyObjectOnly([]), "default");
+    Test_utils.eq("File \"js_json_test.res\", line 342, characters 7-14", classifyObjectOnly({}), "Object");
+    Test_utils.eq("File \"js_json_test.res\", line 343, characters 7-14", classifyObjectOnly("hi"), "String");
   });
   Mocha.test("JSON decodeBoolean", () => {
-    Test_utils.eq("File \"js_json_test.res\", line 334, characters 7-14", Js_json.decodeBoolean("test"), undefined);
-    Test_utils.eq("File \"js_json_test.res\", line 335, characters 7-14", Js_json.decodeBoolean(true), true);
-    Test_utils.eq("File \"js_json_test.res\", line 336, characters 7-14", Js_json.decodeBoolean([]), undefined);
-    Test_utils.eq("File \"js_json_test.res\", line 337, characters 7-14", Js_json.decodeBoolean(null), undefined);
-    Test_utils.eq("File \"js_json_test.res\", line 338, characters 7-14", Js_json.decodeBoolean({}), undefined);
-    Test_utils.eq("File \"js_json_test.res\", line 339, characters 7-14", Js_json.decodeBoolean(1.23), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 347, characters 7-14", Js_json.decodeBoolean("test"), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 348, characters 7-14", Js_json.decodeBoolean(true), true);
+    Test_utils.eq("File \"js_json_test.res\", line 349, characters 7-14", Js_json.decodeBoolean([]), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 350, characters 7-14", Js_json.decodeBoolean(null), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 351, characters 7-14", Js_json.decodeBoolean({}), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 352, characters 7-14", Js_json.decodeBoolean(1.23), undefined);
   });
   Mocha.test("JSON decodeNull", () => {
-    Test_utils.eq("File \"js_json_test.res\", line 343, characters 7-14", Js_json.decodeNull("test"), undefined);
-    Test_utils.eq("File \"js_json_test.res\", line 344, characters 7-14", Js_json.decodeNull(true), undefined);
-    Test_utils.eq("File \"js_json_test.res\", line 345, characters 7-14", Js_json.decodeNull([]), undefined);
-    Test_utils.eq("File \"js_json_test.res\", line 346, characters 7-14", Js_json.decodeNull(null), null);
-    Test_utils.eq("File \"js_json_test.res\", line 347, characters 7-14", Js_json.decodeNull({}), undefined);
-    Test_utils.eq("File \"js_json_test.res\", line 348, characters 7-14", Js_json.decodeNull(1.23), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 356, characters 7-14", Js_json.decodeNull("test"), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 357, characters 7-14", Js_json.decodeNull(true), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 358, characters 7-14", Js_json.decodeNull([]), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 359, characters 7-14", Js_json.decodeNull(null), null);
+    Test_utils.eq("File \"js_json_test.res\", line 360, characters 7-14", Js_json.decodeNull({}), undefined);
+    Test_utils.eq("File \"js_json_test.res\", line 361, characters 7-14", Js_json.decodeNull(1.23), undefined);
   });
   Mocha.test("JSON serialize/deserialize identity", () => {
-    let idtest = obj => Test_utils.eq("File \"js_json_test.res\", line 354, characters 27-34", obj, Js_json.deserializeUnsafe(Js_json.serializeExn(obj)));
+    let idtest = obj => Test_utils.eq("File \"js_json_test.res\", line 367, characters 27-34", obj, Js_json.deserializeUnsafe(Js_json.serializeExn(obj)));
     idtest(undefined);
     idtest({
       hd: [
diff --git a/tests/tests/src/js_json_test.res b/tests/tests/src/js_json_test.res
index 26fa6320d0..0e1bad5add 100644
--- a/tests/tests/src/js_json_test.res
+++ b/tests/tests/src/js_json_test.res
@@ -315,7 +315,7 @@ describe(__MODULE__, () => {
     eq(__LOC__, J.decodeArray(J.number(1.23)), None)
   })
 
-  test("JSON Array/Object switch falls through to wildcard on null", () => {
+  test("JSON Array/Object switch falls through to wildcard on null and array", () => {
     let classifyArrayOrObject = (json: J.t) =>
       switch json {
       | J.Array(items) => Some(items->Js.Array2.length)
@@ -328,6 +328,19 @@ describe(__MODULE__, () => {
     eq(__LOC__, classifyArrayOrObject(J.null), None)
     eq(__LOC__, classifyArrayOrObject(J.array([J.number(1.)])), Some(1))
     eq(__LOC__, classifyArrayOrObject(J.object_(Js.Dict.empty())), Some(0))
+
+    // When there's no Array case, arrays should fall to wildcard
+    let classifyObjectOnly = (json: J.t) =>
+      switch json {
+      | J.Object(_) => "Object"
+      | J.String(_) => "String"
+      | _ => "default"
+      }
+
+    eq(__LOC__, classifyObjectOnly(J.null), "default")
+    eq(__LOC__, classifyObjectOnly(J.array([])), "default")
+    eq(__LOC__, classifyObjectOnly(J.object_(Js.Dict.empty())), "Object")
+    eq(__LOC__, classifyObjectOnly(J.string("hi")), "String")
   })
 
   test("JSON decodeBoolean", () => {