diff --git a/gpt4all-backend/mpt.cpp b/gpt4all-backend/mpt.cpp
index fac3163fe75d..ac4d4282e9f4 100644
--- a/gpt4all-backend/mpt.cpp
+++ b/gpt4all-backend/mpt.cpp
@@ -28,6 +28,7 @@
 #include <sstream>
 #include <thread>
 #include <unordered_set>
+#include <unordered_map>
 #include <regex>
 #include <ggml.h>