diff --git a/serialization/object_serialization.nim b/serialization/object_serialization.nim
index f06ddba..8007482 100644
--- a/serialization/object_serialization.nim
+++ b/serialization/object_serialization.nim
@@ -186,21 +186,21 @@ template GetFieldType(FT: type FieldTag): type =
 template readFieldIMPL[Reader](field: type FieldTag,
                                reader: var Reader): auto =
   mixin readValue
-  type FieldType = GetFieldType(field)
+  # Nim 1.6.12: `type FieldType = GetFieldType(field)` here breaks `NimYAML`.
   {.gcsafe.}: # needed by Nim-1.6
-    # TODO: The `FieldType` coercion below is required to deal
+    # TODO: The `GetFieldType(field)` coercion below is required to deal
     # with a nim bug caused by the distinct `ssz.List` type.
     # It seems to break the generics cache mechanism, which
     # leads to an incorrect return type being reported from
     # the `readFieldIMPL` function.
 
-    # additional notes: putting the FieldType coercion in
+    # additional notes: putting the GetFieldType(field) coercion in
     # `makeFieldReadersTable` will cause problems when orc enabled
     # hence, move it here
-    when distinctBase(FieldType) isnot FieldType:
-      FieldType reader.readValue(FieldType)
+    when distinctBase(GetFieldType(field)) isnot GetFieldType(field):
+      GetFieldType(field) reader.readValue(GetFieldType(field))
     else:
-      reader.readValue(FieldType)
+      reader.readValue(GetFieldType(field))
 
 template writeFieldIMPL*[Writer](writer: var Writer,
                                  fieldTag: type FieldTag,