diff --git a/DynamicObj.sln b/DynamicObj.sln
index b60139b..89c4a52 100644
--- a/DynamicObj.sln
+++ b/DynamicObj.sln
@@ -9,6 +9,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "build", "build", "{39AA72A1
 	ProjectSection(SolutionItems) = preProject
 		build.cmd = build.cmd
 		build.sh = build.sh
+		global.json = global.json
 	EndProjectSection
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".ci", ".ci", "{F82A6F26-517C-4D5E-BD4F-BFC45B5867FE}"
@@ -20,14 +21,7 @@ EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".proj", ".proj", "{C3CF2F15-81C7-4C11-889E-5FCA2C8A981D}"
 	ProjectSection(SolutionItems) = preProject
 		.gitignore = .gitignore
-		build.cmd = build.cmd
-		build.sh = build.sh
-		.config\dotnet-tools.json = .config\dotnet-tools.json
-		global.json = global.json
-		key.snk = key.snk
 		LICENSE = LICENSE
-		package.json = package.json
-		pyproject.toml = pyproject.toml
 		README.md = README.md
 		RELEASE_NOTES.md = RELEASE_NOTES.md
 	EndProjectSection
@@ -37,7 +31,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "docs", "docs", "{42AA66FC-8
 		docs\index.fsx = docs\index.fsx
 	EndProjectSection
 EndProject
-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "CSharpTests", "tests\CSharpTests\CSharpTests.csproj", "{D62D0901-DB69-4C64-AC63-FBBBDCF6BC7D}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "CSharpTests", "tests\CSharpTests\CSharpTests.csproj", "{D62D0901-DB69-4C64-AC63-FBBBDCF6BC7D}"
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tests", "tests", "{988D804A-3A42-4E46-B233-B64F5C22524B}"
 EndProject
diff --git a/src/DynamicObj/DynamicObj.fs b/src/DynamicObj/DynamicObj.fs
index d66879c..4c168ba 100644
--- a/src/DynamicObj/DynamicObj.fs
+++ b/src/DynamicObj/DynamicObj.fs
@@ -253,8 +253,21 @@ type DynamicObj() =
         let overWrite = defaultArg overWrite false
         let rec tryDeepCopyObj (o:obj) =
             match o with
+            | :? int     | :? float   | :? bool    
+            | :? string  | :? char    | :? byte    
+            | :? sbyte   | :? int16   | :? uint16  
+            | :? int32   | :? uint32  | :? int64   
+            | :? uint64  | :? single  
+                -> o
+
+            #if !FABLE_COMPILER_PYTHON
+            // https://github.com/fable-compiler/Fable/issues/3971
+            | :? decimal -> o
+            #endif
+
             | :? DynamicObj as dyn ->
                 let newDyn = DynamicObj()
+                // might want to keep instance props as dynamic props on copy
                 for kv in (dyn.GetProperties(false)) do
                     newDyn.SetProperty(kv.Key, tryDeepCopyObj kv.Value)
                 box newDyn
@@ -264,7 +277,12 @@ type DynamicObj() =
                 box [for dyn in dyns -> tryDeepCopyObj dyn :?> DynamicObj]
             | :? ResizeArray<DynamicObj> as dyns ->
                 box (ResizeArray([for dyn in dyns -> tryDeepCopyObj dyn :?> DynamicObj]))
-            //| :? System.ICloneable as clonable -> clonable.Clone()
+
+            #if !FABLE_COMPILER_PYTHON
+            // https://github.com/fable-compiler/Fable/issues/3972
+            | :? System.ICloneable as clonable -> clonable.Clone()
+            #endif
+
             | _ -> o
 
         this.GetProperties(false)
diff --git a/tests/DynamicObject.Tests/DynamicObjs.fs b/tests/DynamicObject.Tests/DynamicObjs.fs
index 221c8d0..c646c43 100644
--- a/tests/DynamicObject.Tests/DynamicObjs.fs
+++ b/tests/DynamicObject.Tests/DynamicObjs.fs
@@ -486,6 +486,22 @@ let tests_ShallowCopyDynamicProperties = testList "ShallowCopyDynamicProperties"
         Expect.equal a b "copied value was not mutated via reference"
 ]
 
+type DerivedClass(stat: string, dyn: string) as this =
+    inherit DynamicObj()
+    do
+        this.SetProperty("dyn", dyn)
+    member this.Stat = stat
+
+type DerivedClassCloneable(stat: string, dyn: string) as this =
+    inherit DynamicObj()
+    do
+        this.SetProperty("dyn", dyn)
+    member this.Stat = stat
+    interface ICloneable with
+        member this.Clone() =
+            let dyn = this.GetPropertyValue("dyn") |> unbox<string>
+            DerivedClassCloneable(stat, dyn)
+
 let tests_DeepCopyDynamicProperties = testList "DeepCopyDynamicProperties" [
 
     let constructClone (props: seq<string*obj>) =
@@ -498,6 +514,7 @@ let tests_DeepCopyDynamicProperties = testList "DeepCopyDynamicProperties" [
     let bulkMutate (props: seq<string*obj>) (dyn: DynamicObj) =
         props |> Seq.iter (fun (propertyName, propertyValue) -> dyn.SetProperty(propertyName, propertyValue))
 
+
     testList "DynamicObj" [
         testList "Cloneable dynamic properties" [
             testCase "primitives" <| fun _ ->
@@ -534,7 +551,7 @@ let tests_DeepCopyDynamicProperties = testList "DeepCopyDynamicProperties" [
                     "int64", box (int64 -2L)
                     "uint64", box (uint64 2UL)
                     "single", box (single 2.0f)
-                    "decimal", box (decimal 2M) 
+                    "decimal", box (decimal 2M)
                 ]
                 bulkMutate mutatedProps original
                 Expect.notEqual original clone "Original and clone should not be equal after mutating primitive props on original"
@@ -570,7 +587,7 @@ let tests_DeepCopyDynamicProperties = testList "DeepCopyDynamicProperties" [
                 Expect.notEqual original clone "Original and clone should not be equal after mutating DynamicObj prop on original"
                 Expect.sequenceEqual originalProp [|-1; -1; -1|]  "Original should have mutated properties"
                 Expect.equal clonedProp [|1; 2; 3|] "Clone should have original properties"
-            testCase "<DynamicObj list" <| fun _ ->
+            testCase "DynamicObj list" <| fun _ ->
                 ()
             testCase "DynamicObj ResizeArray" <| fun _ ->
                 ()
@@ -588,7 +605,7 @@ let tests_DeepCopyDynamicProperties = testList "DeepCopyDynamicProperties" [
                 ()
             testCase "DynamicObj array" <| fun _ ->
                 ()
-            testCase "<DynamicObj list" <| fun _ ->
+            testCase "DynamicObj list" <| fun _ ->
                 ()
             testCase "DynamicObj ResizeArray" <| fun _ ->
                 ()