diff --git a/ci/scripts/proto/generate.sh b/ci/scripts/proto/generate.sh
index ac4a247..600bcec 100755
--- a/ci/scripts/proto/generate.sh
+++ b/ci/scripts/proto/generate.sh
@@ -7,16 +7,19 @@ REPO_ROOT="$(cd "${SCRIPT_DIR}/../../.." && pwd)"
 API_DIR="${REPO_ROOT}/api"
 PROTO_DIR="./proto"
 PROTOC_BIN="${PROTOC:-protoc}"
-PROTOC_INCLUDE="${PROTOC_INCLUDE:-/usr/include}"
-if [ ! -f "${PROTOC_INCLUDE}/google/protobuf/timestamp.proto" ]; then
-for candidate in /usr/include /usr/local/include /usr/lib/include /usr/local/share/include "$(dirname "$(command -v protoc)")/../include"; do
+PROTOC_INCLUDE="${PROTOC_INCLUDE:-}"
+if [ -z "${PROTOC_INCLUDE}" ]; then
+  PROTOC_INCLUDE="$("${PROTOC_BIN}" --print_include_path 2>/dev/null || true)"
+fi
+if [ -z "${PROTOC_INCLUDE}" ] || [ ! -f "${PROTOC_INCLUDE}/google/protobuf/timestamp.proto" ]; then
+  for candidate in /usr/include /usr/local/include /usr/lib/include /usr/local/share/include "$(dirname "${PROTOC_BIN}")/../include"; do
     if [ -f "${candidate}/google/protobuf/timestamp.proto" ]; then
       PROTOC_INCLUDE="${candidate}"
       break
     fi
   done
 fi
-if [ ! -f "${PROTOC_INCLUDE}/google/protobuf/timestamp.proto" ]; then
+if [ -z "${PROTOC_INCLUDE}" ] || [ ! -f "${PROTOC_INCLUDE}/google/protobuf/timestamp.proto" ]; then
   echo "[proto] failed to locate google/protobuf well-known types; set PROTOC_INCLUDE" >&2
   exit 1
 fi