diff --git a/data/specifications/isa.yaml b/data/specifications/isa.yaml
index 289ffca..3e00865 100644
--- a/data/specifications/isa.yaml
+++ b/data/specifications/isa.yaml
@@ -19,3 +19,7 @@ versions:
     date: "2020-05-02"
     download: "https://files.openpower.foundation/s/bo728kgiWfgMHAr"
     description: "Initial release."
+  - number: "3.1b"
+    date: "2021-09-14"
+    download: "https://files.openpower.foundation/s/dAYSdGzTfW4j2r2"
+    description: "Incorporate errata."