diff --git a/.github/workflows/build-cloe.yaml b/.github/workflows/build-cloe.yaml
index bc54e94d..df1e6937 100644
--- a/.github/workflows/build-cloe.yaml
+++ b/.github/workflows/build-cloe.yaml
@@ -44,7 +44,7 @@ jobs:
           #    This cannot be currently enabled because of a Conan deficiency in v1.
           #    Once all build tooling is based on Conan v2, we can re-enable this use-case.
           #    Until then, use the previous target for this use-case.
-          - "export-vendor editable-select build-all smoketest TEST_CONANFILES=tests/conanfile_deployment.py"
+          - "export-vendor editable-select fetch-protobuf build-all smoketest TEST_CONANFILES=tests/conanfile_deployment.py"
     env:
       CONAN_NON_INTERACTIVE: "yes"
       DEBIAN_FRONTEND: noninteractive
diff --git a/Makefile b/Makefile
index 30ca2c30..f46b1399 100644
--- a/Makefile
+++ b/Makefile
@@ -129,6 +129,14 @@ purge-all:
 package-all:
 	conan install $(CONAN_OPTIONS) --install-folder $(DEPLOY_DIR) --build=missing --build=outdated $(DEPLOY_LOCKFILE_SOURCE)
 
+.PHONY: fetch-protobuf
+fetch-protobuf:
+	# This is needed for `build-all` to work with Conan v1.
+	# If protobuf is not already available, then conan will want to build it,
+	# but it won't find it in the lockfile, because a package cannot be in
+	# host and build context simultaneously.
+	conan install --build-require protobuf/3.21.12@_/_
+
 # Development targets ---------------------------------------------------------
 help::
 	$(call print_help_section, "Available development targets")