diff --git a/documentation/source/library-reference/common-dylan/common-extensions.rst b/documentation/source/library-reference/common-dylan/common-extensions.rst
index 7bb3fffe6..e5d853c3d 100644
--- a/documentation/source/library-reference/common-dylan/common-extensions.rst
+++ b/documentation/source/library-reference/common-dylan/common-extensions.rst
@@ -132,7 +132,7 @@ The extensions are:
 .. generic-function:: condition-to-string
    :open:
 
-   Returns a string representation of a condition object.
+   Returns a :drm:`<string>` representation of a condition object.
 
    :signature: condition-to-string *condition* => *string*
 
@@ -142,9 +142,15 @@ The extensions are:
    :description:
 
      Returns a string representation of a general instance of
-     :drm:`<condition>`. There is a method on
-     :class:`<format-string-condition>` and method on
-     :drm:`<type-error>`.
+     :drm:`<condition>`.
+
+     Note that it is often not necessary to write a method on this generic
+     function for your condition classes because you can use the method
+     provided by :class:`<simple-condition>`, usually via one of its
+     subclasses, :drm:`<simple-error>`, :drm:`<simple-warning>`, or
+     :drm:`<simple-restart>`. Simply make your condition a subclass of one of
+     these classes and provide the ``format-string:`` and ``format-arguments:``
+     init keywords.
 
 .. macro:: debug-assert
    :statement:
diff --git a/sources/common-dylan/format.dylan b/sources/common-dylan/format.dylan
index 6860ddcfa..cdf63103f 100644
--- a/sources/common-dylan/format.dylan
+++ b/sources/common-dylan/format.dylan
@@ -588,13 +588,6 @@ define method condition-to-string
         condition-format-arguments(condition))
 end method condition-to-string;
 
-define method condition-to-string
-    (error :: <type-error>) => (string :: <string>)
-  format-to-string("%= is not of type %=",
-                   type-error-value(error),
-                   type-error-expected-type(error))
-end method condition-to-string;
-
 define method print-pretty-name
     (buffer :: <string-buffer>, condition :: <condition>)
  => ()
diff --git a/sources/common-dylan/tests/condition-test-utilities.dylan b/sources/common-dylan/tests/condition-test-utilities.dylan
index d9ca4d8ec..c47811638 100644
--- a/sources/common-dylan/tests/condition-test-utilities.dylan
+++ b/sources/common-dylan/tests/condition-test-utilities.dylan
@@ -66,6 +66,12 @@ define method test-condition (condition :: <type-error>) => ()
             ))
 end method test-condition;
 
+define method make-condition (class == <type-error>) => (c :: <type-error>)
+  make(<type-error>,
+       value: #"type-error-value",
+       type: <string>)
+end method;
+
 define method test-condition (condition :: <simple-warning>) => ()
   next-method();
   do(method (function) function(condition) end,
diff --git a/sources/dylan/condition-extras.dylan b/sources/dylan/condition-extras.dylan
index 5d9e09fb8..be53f97ff 100644
--- a/sources/dylan/condition-extras.dylan
+++ b/sources/dylan/condition-extras.dylan
@@ -89,9 +89,13 @@ end method abort;
 
 /// TYPE-ERRORS
 
-define open class <type-error> (<error>, <format-string-condition>)  // Should be sealed?
-  constant slot type-error-value, init-keyword: value:;
-  constant slot type-error-expected-type :: <type>, init-keyword: type:;
+// Note that the DRM only mentions <error> as a superclass. Speculation: we
+// additionally subclass <simple-condition> because there is special support
+// for its condition-format-string and condition-format-arguments in the
+// debugger manager.
+define sealed class <type-error> (<error>, <simple-condition>)
+  constant slot type-error-value, required-init-keyword: value:;
+  constant slot type-error-expected-type :: <type>, required-init-keyword: type:;
 end class <type-error>;
 
 define method make
diff --git a/sources/dylan/tests/specification.dylan b/sources/dylan/tests/specification.dylan
index 81daafbb3..46c50f63d 100644
--- a/sources/dylan/tests/specification.dylan
+++ b/sources/dylan/tests/specification.dylan
@@ -238,7 +238,7 @@ define interface-specification-suite dylan-conditions-specification-suite ()
   open abstract class <serious-condition> (<condition>);
   sealed instantiable class <simple-error> (<error>);
   sealed instantiable class <simple-warning> (<warning>);
-  sealed instantiable class <type-error> (<error>);
+  sealed instantiable class <type-error> (<error>); // make-test-instance method below.
   open abstract class <warning> (<condition>);
 
   /// Restarts
@@ -286,6 +286,12 @@ define interface-specification-suite dylan-conditions-specification-suite ()
     expected-to-fail-reason: "https://github.com/dylan-lang/opendylan/issues/1295";
 end dylan-conditions-specification-suite;
 
+define sideways method make-test-instance (class == <type-error>) => (err :: <type-error>)
+  make(<type-error>,
+       value: #"type-error-value",
+       type: <string>)
+end method;
+
 //--- Bindings not defined by the DRM
 //---*** Are there any others?