diff --git a/formats_err/expr_sizeof_cyclic_dependency.ksy b/formats_err/expr_sizeof_cyclic_dependency.ksy
new file mode 100644
index 00000000..b10202bb
--- /dev/null
+++ b/formats_err/expr_sizeof_cyclic_dependency.ksy
@@ -0,0 +1,10 @@
+# expr_sizeof_cyclic_dependency.ksy: /seq/0/if:
+# 	error: unable to derive sizeof for type `expr_sizeof_cyclic_dependency`: dynamic sized type
+#
+meta:
+  id: expr_sizeof_cyclic_dependency
+  -gh-issue: https://github.com/kaitai-io/kaitai_struct/issues/927
+seq:
+  - id: value
+    size: 2
+    if: _sizeof == 1
diff --git a/formats_err/expr_sizeof_value_dynamic3.ksy b/formats_err/expr_sizeof_value_dynamic3.ksy
index 0d0dbfe2..34312a6d 100644
--- a/formats_err/expr_sizeof_value_dynamic3.ksy
+++ b/formats_err/expr_sizeof_value_dynamic3.ksy
@@ -1,14 +1,16 @@
-# ?
+# expr_sizeof_value_dynamic3.ksy: /instances/body_sizeof/value:
+# 	error: unable to derive sizeof of `Name(identifier(body))`: dynamic sized type
+#
 meta:
   id: expr_sizeof_value_dynamic3
   endian: le
 seq:
-  - id: num
+  - id: num_body
     type: u2
   - id: body
     type: u1
     repeat: expr
-    repeat-expr: num
+    repeat-expr: num_body
 instances:
   body_sizeof:
     value: body._sizeof