diff --git a/src/testdir/test_vim9_class.vim b/src/testdir/test_vim9_class.vim
index 4ce9fcd..d8a3fa3 100644
--- a/src/testdir/test_vim9_class.vim
+++ b/src/testdir/test_vim9_class.vim
@@ -11546,6 +11546,54 @@
     Fn(null_object)
   END
   v9.CheckScriptFailure(lines, 'E1360: Using a null object', 1)
+
+  # Try to change a const object variable using a "any" variable
+  lines =<< trim END
+    vim9script
+    class A
+      public const v1: number = 123
+    endclass
+
+    def Fn(o: any)
+      o.v1 = 321
+    enddef
+
+    var a = A.new()
+    Fn(a)
+  END
+  v9.CheckScriptFailure(lines, 'E1409: Cannot change read-only variable "v1" in class "A"', 1)
+
+  # Try to change a final object variable using a "any" variable
+  lines =<< trim END
+    vim9script
+    class A
+      public final v1: number = 123
+    endclass
+
+    def Fn(o: any)
+      o.v1 = 321
+    enddef
+
+    var a = A.new()
+    Fn(a)
+  END
+  v9.CheckScriptFailure(lines, 'E1409: Cannot change read-only variable "v1" in class "A"', 1)
+
+  # Assign a different type of value to an "any" type object variable
+  lines =<< trim END
+    vim9script
+    class A
+      public var v1: list<any> = [1, 2]
+    endclass
+
+    def Fn(o: A)
+      o.v1 = 'abc'
+    enddef
+
+    var a = A.new()
+    Fn(a)
+  END
+  v9.CheckScriptFailure(lines, 'E1012: Type mismatch; expected list<any> but got string', 1)
 enddef
 
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker
diff --git a/src/version.c b/src/version.c
index 7985985..f2e9473 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    861,
+/**/
     860,
 /**/
     859,
diff --git a/src/vim9execute.c b/src/vim9execute.c
index da03d5e..7ab6813 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -2271,6 +2271,7 @@
 		    // Get the current function
 		    ufunc_T *ufunc = (((dfunc_T *)def_functions.ga_data)
 					+ ectx->ec_dfunc_idx)->df_ufunc;
+		    where_T where = WHERE_INIT;
 
 		    // Check whether the member variable is writeable
 		    if ((m->ocm_access != VIM_ACCESS_ALL) &&
@@ -2283,6 +2284,12 @@
 			emsg_var_cl_define(msg, m->ocm_name, 0, cl);
 			status = FAIL;
 		    }
+		    // Fail if the variable is a const or final or the type
+		    // is not compatible
+		    else if (oc_var_check_ro(cl, m) ||
+			     check_typval_type(m->ocm_type, tv, where)
+								== FAIL)
+			status = FAIL;
 		    else
 			lidx = m_idx;
 		}