diff --git a/shop3/decls.lisp b/shop3/decls.lisp
index 89e6594e..0df8efd0 100644
--- a/shop3/decls.lisp
+++ b/shop3/decls.lisp
@@ -913,3 +913,12 @@ task keyword of TASK and LIBRARY-TASK are the same.")
            (member thing '(&optional &rest) :test #'eq)))
     (if (find-if #'rest-or-optional-p types) `(values ,@types)
         `(values ,@types &optional))))
+
+;;;---------------------------------------------------------------------------
+;;; CL:CHECK-TYPE messes up SBCL's type checking, because on continuation
+;;; it allows the user to supply an object of a new type.  Change it to just
+;;; raise a type error. [2024/08/02:rpg]
+;;;---------------------------------------------------------------------------
+(defmacro check-type (place type)
+  `(unless (typep ,place ',type)
+     (error 'type-error :datum ,place :expected-type ',type)))
diff --git a/shop3/package.lisp b/shop3/package.lisp
index 8fa18812..c1b36efb 100644
--- a/shop3/package.lisp
+++ b/shop3/package.lisp
@@ -63,6 +63,8 @@
     (:documentation "The SHOP3 package is the package that exposes SHOP3's API.")
     (:use :common-lisp :shop3.unifier :shop3.common :shop3.theorem-prover
           :iterate)
+    ;; override this...
+    (:shadow #:check-type)
     (:import-from #:shop3.common #:domain-core)
     (:import-from #:shop3.theorem-prover #:+numerical-comparisons+
                   #:fluent-value