diff --git a/cheriot/cheriot_getter_helpers.h b/cheriot/cheriot_getter_helpers.h
index d6546cb..a71ac74 100644
--- a/cheriot/cheriot_getter_helpers.h
+++ b/cheriot/cheriot_getter_helpers.h
@@ -40,7 +40,11 @@
 
 template <typename M, typename E, typename G>
 inline void Insert(M &map, E entry, G getter) {
-  map.insert(std::make_pair(static_cast<int>(entry), getter));
+  if (!map.contains(static_cast<int>(entry))) {
+    map.insert(std::make_pair(static_cast<int>(entry), getter));
+  } else {
+    map.at(static_cast<int>(entry)) = getter;
+  }
 }
 
 // Generic helper functions to create register operands.
diff --git a/repos.bzl b/repos.bzl
index f6f50cf..a563a21 100644
--- a/repos.bzl
+++ b/repos.bzl
@@ -22,7 +22,7 @@
     if not native.existing_rule("com_google_mpact-riscv"):
         http_archive(
             name = "com_google_mpact-riscv",
-            sha256 = "72f0b34338e255257d3e7f3ae3dba368f4a0233a79bd16087453544ec8ef3502",
-            strip_prefix = "mpact-riscv-bf27fab72381a7a0bf3ab4cdb68d483c5afd162d",
-            url = "https://github.com/google/mpact-riscv/archive/bf27fab72381a7a0bf3ab4cdb68d483c5afd162d.tar.gz",
+            sha256 = "b708de08f8371ad38d30eafb71951199d96de0901753398b2f923303e2938990",
+            strip_prefix = "mpact-riscv-39ca15d0f1265758fdfbef4b6cfd5d321988aeac",
+            url = "https://github.com/google/mpact-riscv/archive/39ca15d0f1265758fdfbef4b6cfd5d321988aeac.tar.gz",
         )