diff --git a/.tool-versions b/.tool-versions
index 4933a41..a02c9a2 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1 +1 @@
-golang 1.18
+golang 1.22.3
diff --git a/Dockerfile b/Dockerfile
index 791a922..4a5dd18 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,7 +2,7 @@
 ###############################
 # Build the doctree Go binary #
 ###############################
-FROM golang:1.18-alpine as builder
+FROM golang:1.22-alpine@sha256:cdc86d9f363e8786845bea2040312b4efa321b828acdeb26f393faa864d887b0 as builder
 
 RUN apk add --no-cache git build-base
 COPY . /doctree