diff --git a/ivtest/ivltests/sv_class_compat1.v b/ivtest/ivltests/sv_class_compat1.v
new file mode 100644
index 000000000..be4d94804
--- /dev/null
+++ b/ivtest/ivltests/sv_class_compat1.v
@@ -0,0 +1,31 @@
+// Check that an object can be assigned to a variable of its base class type
+
+module test;
+
+  class B;
+    int x;
+
+    task t;
+      $display("PASSED");
+    endtask
+  endclass
+
+  class C extends B;
+    int y;
+
+    task t;
+      $display("FAILED");
+    endtask
+  endclass
+
+  B b;
+  C c;
+
+  initial begin
+    c = new;
+    b = c;
+
+    b.t;
+  end
+
+endmodule
diff --git a/ivtest/ivltests/sv_class_compat2.v b/ivtest/ivltests/sv_class_compat2.v
new file mode 100644
index 000000000..29eb7bf59
--- /dev/null
+++ b/ivtest/ivltests/sv_class_compat2.v
@@ -0,0 +1,40 @@
+// Check that an object can be assigned to a variable of base class across more
+// than one hierarchy level
+
+module test;
+
+  class B;
+    int x;
+
+    task t;
+      $display("PASSED");
+    endtask
+  endclass
+
+  class C extends B;
+    int y;
+
+    task t;
+      $display("FAILED");
+    endtask
+  endclass
+
+  class D extends C;
+    int z;
+
+    task t;
+      $display("FAILED");
+    endtask
+  endclass
+
+  B b;
+  D d;
+
+  initial begin
+    d = new;
+    b = d;
+
+    b.t;
+  end
+
+endmodule
diff --git a/ivtest/ivltests/sv_class_compat_fail1.v b/ivtest/ivltests/sv_class_compat_fail1.v
new file mode 100644
index 000000000..e96f018a8
--- /dev/null
+++ b/ivtest/ivltests/sv_class_compat_fail1.v
@@ -0,0 +1,22 @@
+// Check that an error is reported when trying to assign an object to variable
+// of an unrelated class type
+
+module test;
+
+  class B;
+    int x;
+  endclass
+
+  class C;
+    int y;
+  endclass
+
+  B b;
+  C c;
+
+  initial begin
+    c = new;
+    b = c; // This should fail, both classes are unrelated
+  end
+
+endmodule
diff --git a/ivtest/ivltests/sv_class_compat_fail2.v b/ivtest/ivltests/sv_class_compat_fail2.v
new file mode 100644
index 000000000..e8563b47f
--- /dev/null
+++ b/ivtest/ivltests/sv_class_compat_fail2.v
@@ -0,0 +1,22 @@
+// Check that an error is reported when trying when trying to assign an object
+// of a base class to a variable of a inherited class.
+
+module test;
+
+  class B;
+    int x;
+  endclass
+
+  class C extends B;
+    int y;
+  endclass
+
+  B b;
+  C c;
+
+  initial begin
+    b = new;
+    c = b; // This should fail, B is a base class of C
+  end
+
+endmodule
diff --git a/ivtest/ivltests/sv_class_compat_fail3.v b/ivtest/ivltests/sv_class_compat_fail3.v
new file mode 100644
index 000000000..a7301386e
--- /dev/null
+++ b/ivtest/ivltests/sv_class_compat_fail3.v
@@ -0,0 +1,27 @@
+// Check that an error is reported when trying to assign an object to a variable
+// that shares a common base class but is not directly related.
+
+module test;
+
+  class B;
+    int x;
+  endclass
+
+  class C extends B;
+    int y;
+  endclass
+
+  class D extends B;
+    int z;
+  endclass
+
+  C c;
+  D d;
+
+  initial begin
+    c = new;
+    d = c; // This should fail, both C and D inherit from B, but there is no
+           // direct relationship.
+  end
+
+endmodule
diff --git a/ivtest/regress-sv.list b/ivtest/regress-sv.list
index c7dea8134..efebe53e8 100644
--- a/ivtest/regress-sv.list
+++ b/ivtest/regress-sv.list
@@ -531,6 +531,11 @@ sv_class21		normal,-g2009		ivltests
 sv_class22		normal,-g2009		ivltests
 sv_class23		normal,-g2009		ivltests
 sv_class24		normal,-g2009		ivltests
+sv_class_compat1	normal,-g2009		ivltests
+sv_class_compat2	normal,-g2009		ivltests
+sv_class_compat_fail1	CE,-g2009		ivltests
+sv_class_compat_fail2	CE,-g2009		ivltests
+sv_class_compat_fail3	CE,-g2009		ivltests
 sv_class_constructor1	normal,-g2009		ivltests
 sv_class_constructor_fail   CE,-g2009		ivltests
 sv_class_empty_item	normal,-g2009		ivltests
diff --git a/ivtest/regress-vlog95.list b/ivtest/regress-vlog95.list
index 323a0cb1a..324a6d41e 100644
--- a/ivtest/regress-vlog95.list
+++ b/ivtest/regress-vlog95.list
@@ -404,6 +404,8 @@ sv_class21		CE,-g2009		ivltests
 sv_class22		CE,-g2009		ivltests
 sv_class23		CE,-g2009		ivltests
 sv_class24		CE,-g2009		ivltests
+sv_class_compat1	CE,-g2009		ivltests
+sv_class_compat2	CE,-g2009		ivltests
 sv_class_constructor1	CE,-g2009		ivltests
 sv_class_empty_item	CE,-g2009		ivltests
 sv_class_extends_scoped	CE,-g2009		ivltests
diff --git a/netclass.cc b/netclass.cc
index 3365a8949..99ad5d68a 100644
--- a/netclass.cc
+++ b/netclass.cc
@@ -195,3 +195,14 @@ const NetExpr* netclass_t::get_parameter(Design *des, perm_string name,
 {
       return class_scope_->get_parameter(des, name, par_type);
 }
+
+bool netclass_t::test_compatibility(ivl_type_t that) const
+{
+      for (const netclass_t *class_type = dynamic_cast<const netclass_t *>(that);
+	    class_type; class_type = class_type->get_super()) {
+	    if (class_type == this)
+		  return true;
+      }
+
+      return false;
+}
diff --git a/netclass.h b/netclass.h
index 0c598fe32..a34487e9b 100644
--- a/netclass.h
+++ b/netclass.h
@@ -119,6 +119,9 @@ class netclass_t : public ivl_type_s {
       void set_virtual(bool virtual_class) { virtual_class_ = virtual_class; }
       bool is_virtual() const { return virtual_class_; }
 
+    protected:
+      bool test_compatibility(ivl_type_t that) const;
+
     private:
       perm_string name_;
 	// If this is derived from another base class, point to it