diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 47047d6..a7c96ad 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -46,6 +46,9 @@ jobs:
         with:
           go-version: "1.22"
 
+      - name: Install Protoc
+        uses: arduino/setup-protoc@v3
+
       - uses: awalsh128/cache-apt-pkgs-action@v1
         with:
           packages: protobuf-compiler libprotobuf-dev
diff --git a/Makefile b/Makefile
index 83fd6a1..2fb96ee 100644
--- a/Makefile
+++ b/Makefile
@@ -88,7 +88,7 @@ ttrpc:
 	cd api/shim/v1; protoc --go_out=. --go_opt=paths=source_relative \
 	--ttrpc_out=. --plugin=protoc-gen-ttrpc=`which protoc-gen-go-ttrpc` \
 	--ttrpc_opt=paths=source_relative *.proto -I. \
-	-I ${GOPATH}/pkg/mod/github.com/prometheus/client_model@v0.5.0
+	-I $(shell go env GOMODCACHE)/github.com/prometheus/client_model@v0.5.0
 
 # to improve reproducibility of the bpf builds, we dump the vmlinux.h and
 # store it compressed in git instead of dumping it during the build.