diff --git a/lib/gssapi/decapsulate.c b/lib/gssapi/decapsulate.c
index 3a5d97158..e006f3863 100644
--- a/lib/gssapi/decapsulate.c
+++ b/lib/gssapi/decapsulate.c
@@ -2,6 +2,42 @@
 
 RCSID("$Id$");
 
+OM_uint32
+gssapi_krb5_verify_header(u_char **str,
+			  size_t total_len,
+			  u_char *type)
+{
+    size_t len, len_len, mech_len, foo;
+    int e;
+    u_char *p = *str;
+
+    if (*p++ != 0x60)
+	return GSS_S_DEFECTIVE_TOKEN;
+    e = der_get_length (p, total_len - 1, &len, &len_len);
+    if (e || 1 + len_len + len != total_len)
+	abort ();
+    p += len_len;
+    if (*p++ != 0x06)
+	return GSS_S_DEFECTIVE_TOKEN;
+    e = der_get_length (p, total_len - 1 - len_len - 1,
+			&mech_len, &foo);
+    if (e)
+	abort ();
+    p += foo;
+    if (mech_len != GSS_KRB5_MECHANISM->length)
+	return GSS_S_BAD_MECH;
+    if (memcmp(p,
+	       GSS_KRB5_MECHANISM->elements,
+	       GSS_KRB5_MECHANISM->length) != 0)
+	return GSS_S_BAD_MECH;
+    p += mech_len;
+    if (memcmp (p, type, 2) != 0)
+	return GSS_S_DEFECTIVE_TOKEN;
+    p += 2;
+    *str = p;
+    return GSS_S_COMPLETE;
+}
+
 /*
  * Remove the GSS-API wrapping from `in_token' giving `out_data.
  * Does not copy data, so just free `in_token'.
@@ -14,23 +50,18 @@ gssapi_krb5_decapsulate(
 			u_char *type
 )
 {
-  u_char *p;
-  size_t len;
+    u_char *p;
+    OM_uint32 ret;
 
-  p = input_token_buffer->value;
-  len = GSS_KRB5_MECHANISM->length + 6;
-  if (
-      input_token_buffer->length < len
-      || memcmp (p, "\x60\x07\x06\x05", 4) != 0
-      || memcmp (p + 4, GSS_KRB5_MECHANISM->elements,
-		 GSS_KRB5_MECHANISM->length) != 0)
-    return GSS_S_BAD_MECH;
-  if (memcmp (p + 4 + GSS_KRB5_MECHANISM->length,
-	      type, 2) != 0)
-    return GSS_S_DEFECTIVE_TOKEN;
+    p = input_token_buffer->value;
+    ret = gssapi_krb5_verify_header(&p,
+				    input_token_buffer->length,
+				    type);
+    if (ret)
+	return ret;
 
-  out_data->length = input_token_buffer->length - len;
-  out_data->data   = (u_char *)input_token_buffer->value  + len;
-
-  return GSS_S_COMPLETE;
+    out_data->length = input_token_buffer->length -
+	(p - (u_char *)input_token_buffer->value);
+    out_data->data   = p;
+    return GSS_S_COMPLETE;
 }
diff --git a/lib/gssapi/krb5/decapsulate.c b/lib/gssapi/krb5/decapsulate.c
index 3a5d97158..e006f3863 100644
--- a/lib/gssapi/krb5/decapsulate.c
+++ b/lib/gssapi/krb5/decapsulate.c
@@ -2,6 +2,42 @@
 
 RCSID("$Id$");
 
+OM_uint32
+gssapi_krb5_verify_header(u_char **str,
+			  size_t total_len,
+			  u_char *type)
+{
+    size_t len, len_len, mech_len, foo;
+    int e;
+    u_char *p = *str;
+
+    if (*p++ != 0x60)
+	return GSS_S_DEFECTIVE_TOKEN;
+    e = der_get_length (p, total_len - 1, &len, &len_len);
+    if (e || 1 + len_len + len != total_len)
+	abort ();
+    p += len_len;
+    if (*p++ != 0x06)
+	return GSS_S_DEFECTIVE_TOKEN;
+    e = der_get_length (p, total_len - 1 - len_len - 1,
+			&mech_len, &foo);
+    if (e)
+	abort ();
+    p += foo;
+    if (mech_len != GSS_KRB5_MECHANISM->length)
+	return GSS_S_BAD_MECH;
+    if (memcmp(p,
+	       GSS_KRB5_MECHANISM->elements,
+	       GSS_KRB5_MECHANISM->length) != 0)
+	return GSS_S_BAD_MECH;
+    p += mech_len;
+    if (memcmp (p, type, 2) != 0)
+	return GSS_S_DEFECTIVE_TOKEN;
+    p += 2;
+    *str = p;
+    return GSS_S_COMPLETE;
+}
+
 /*
  * Remove the GSS-API wrapping from `in_token' giving `out_data.
  * Does not copy data, so just free `in_token'.
@@ -14,23 +50,18 @@ gssapi_krb5_decapsulate(
 			u_char *type
 )
 {
-  u_char *p;
-  size_t len;
+    u_char *p;
+    OM_uint32 ret;
 
-  p = input_token_buffer->value;
-  len = GSS_KRB5_MECHANISM->length + 6;
-  if (
-      input_token_buffer->length < len
-      || memcmp (p, "\x60\x07\x06\x05", 4) != 0
-      || memcmp (p + 4, GSS_KRB5_MECHANISM->elements,
-		 GSS_KRB5_MECHANISM->length) != 0)
-    return GSS_S_BAD_MECH;
-  if (memcmp (p + 4 + GSS_KRB5_MECHANISM->length,
-	      type, 2) != 0)
-    return GSS_S_DEFECTIVE_TOKEN;
+    p = input_token_buffer->value;
+    ret = gssapi_krb5_verify_header(&p,
+				    input_token_buffer->length,
+				    type);
+    if (ret)
+	return ret;
 
-  out_data->length = input_token_buffer->length - len;
-  out_data->data   = (u_char *)input_token_buffer->value  + len;
-
-  return GSS_S_COMPLETE;
+    out_data->length = input_token_buffer->length -
+	(p - (u_char *)input_token_buffer->value);
+    out_data->data   = p;
+    return GSS_S_COMPLETE;
 }