diff --git a/src/typval.c b/src/typval.c
index b19140d..21ecd87 100644
--- a/src/typval.c
+++ b/src/typval.c
@@ -591,7 +591,6 @@
 	case VAR_NUMBER:
 	case VAR_BOOL:
 	case VAR_SPECIAL:
-	case VAR_VOID:
 	    to->vval.v_number = from->vval.v_number;
 	    break;
 	case VAR_FLOAT:
@@ -664,6 +663,9 @@
 		++to->vval.v_dict->dv_refcount;
 	    }
 	    break;
+	case VAR_VOID:
+	    emsg(_(e_cannot_use_void_value));
+	    break;
 	case VAR_UNKNOWN:
 	case VAR_ANY:
 	    internal_error_no_abort("copy_tv(UNKNOWN)");