diff --git a/website/api/defines.html b/website/api/defines.html
index 8389d159..96f6720e 100644
--- a/website/api/defines.html
+++ b/website/api/defines.html
@@ -87,17 +87,7 @@ typedef struct duk_number_list_entry duk_number_list_entry;
 
 <h2>Error codes</h2>
 <pre class="c-code">
-/* Internal error codes */
 #define DUK_ERR_NONE                 0    /* no error (e.g. from duk_get_error_code()) */
-#define DUK_ERR_UNIMPLEMENTED_ERROR  50   /* UnimplementedError */
-#define DUK_ERR_UNSUPPORTED_ERROR    51   /* UnsupportedError */
-#define DUK_ERR_INTERNAL_ERROR       52   /* InternalError */
-#define DUK_ERR_ALLOC_ERROR          53   /* AllocError */
-#define DUK_ERR_ASSERTION_ERROR      54   /* AssertionError */
-#define DUK_ERR_API_ERROR            55   /* APIError */
-#define DUK_ERR_UNCAUGHT_ERROR       56   /* UncaughtError */
-
-/* Ecmascript E5 specification error codes */
 #define DUK_ERR_ERROR                100  /* Error */
 #define DUK_ERR_EVAL_ERROR           101  /* EvalError */
 #define DUK_ERR_RANGE_ERROR          102  /* RangeError */
@@ -110,13 +100,6 @@ typedef struct duk_number_list_entry duk_number_list_entry;
 <h2>Return codes from Duktape/C functions</h2>
 <pre class="c-code">
 /* Return codes for C functions */
-#define DUK_RET_UNIMPLEMENTED_ERROR  (-DUK_ERR_UNIMPLEMENTED_ERROR)
-#define DUK_RET_UNSUPPORTED_ERROR    (-DUK_ERR_UNSUPPORTED_ERROR)
-#define DUK_RET_INTERNAL_ERROR       (-DUK_ERR_INTERNAL_ERROR)
-#define DUK_RET_ALLOC_ERROR          (-DUK_ERR_ALLOC_ERROR)
-#define DUK_RET_ASSERTION_ERROR      (-DUK_ERR_ASSERTION_ERROR)
-#define DUK_RET_API_ERROR            (-DUK_ERR_API_ERROR)
-#define DUK_RET_UNCAUGHT_ERROR       (-DUK_ERR_UNCAUGHT_ERROR)
 #define DUK_RET_ERROR                (-DUK_ERR_ERROR)
 #define DUK_RET_EVAL_ERROR           (-DUK_ERR_EVAL_ERROR)
 #define DUK_RET_RANGE_ERROR          (-DUK_ERR_RANGE_ERROR)
diff --git a/website/api/duk_get_error_code.yaml b/website/api/duk_get_error_code.yaml
index 05b0af9c..e134bad5 100644
--- a/website/api/duk_get_error_code.yaml
+++ b/website/api/duk_get_error_code.yaml
@@ -11,8 +11,11 @@ summary: |
   based on which <code>Error</code> subclass the value inherits from.  For example,
   if the value at the stack top is an user-defined error which inherits from
   <code>ReferenceError</code>, the return value will be <code>DUK_ERR_REFERENCE_ERROR</code>.
-  If the value is not an object, does not inherit from <code>Error</code>, or <code>idx</code>
-  is invalid, returns 0 (= <code>DUK_ERR_NONE</code>).</p>
+  If the value inherits from <code>Error</code> but doesn't inherit from any of
+  the standard subclasses (EvalError, RangeError, ReferenceError, SyntaxError,
+  TypeError, URIError) <code>DUK_ERR_ERROR</code> is returned.
+  If the value is not an object, does not inherit from <code>Error</code>, or
+  <code>idx</code> is invalid, returns 0 (= <code>DUK_ERR_NONE</code>).</p>
 
 example: |
   if (duk_get_error_code(ctx, -3) == DUK_ERR_URI_ERROR) {