diff --git a/Modules/_blake2/blake2b_impl.c b/Modules/_blake2/blake2b_impl.c
index 8c28249d561c08..7f8ea44bc5fd63 100644
--- a/Modules/_blake2/blake2b_impl.c
+++ b/Modules/_blake2/blake2b_impl.c
@@ -407,6 +407,8 @@ static PyType_Slot blake2b_type_slots[] = {
     {0,0}
 };
 
+// Using PyType_GetModuleState() on this type is safe since
+// it cannot be subclassed: it does not have the Py_TPFLAGS_BASETYPE flag.
 PyType_Spec blake2b_type_spec = {
     .name = "_blake2.blake2b",
     .basicsize =  sizeof(BLAKE2bObject),
diff --git a/Modules/_blake2/blake2s_impl.c b/Modules/_blake2/blake2s_impl.c
index e4146997da33d4..ffaf4315133061 100644
--- a/Modules/_blake2/blake2s_impl.c
+++ b/Modules/_blake2/blake2s_impl.c
@@ -406,6 +406,8 @@ static PyType_Slot blake2s_type_slots[] = {
     {0,0}
 };
 
+// Using PyType_GetModuleState() on this type is safe since
+// it cannot be subclassed: it does not have the Py_TPFLAGS_BASETYPE flag.
 PyType_Spec blake2s_type_spec = {
     .name = "_blake2.blake2s",
     .basicsize =  sizeof(BLAKE2sObject),