diff --git a/spec/internal/grpc.lua b/spec/internal/grpc.lua
index ec0f413ccb2..0c5bbd41bf1 100644
--- a/spec/internal/grpc.lua
+++ b/spec/internal/grpc.lua
@@ -9,6 +9,9 @@ local CONSTANTS = require("spec.internal.constants")
 local function make(workdir, specs)
   workdir = pl_path.normpath(workdir or pl_path.currentdir())
 
+  os.execute("which protoc")
+  assert(os.execute(string.format("cd %s make clean && make all", workdir)))
+
   for _, spec in ipairs(specs) do
     local ok, _, stderr = shell.run(string.format("cd %s; %s", workdir, spec.cmd), nil, 0)
     assert(ok, stderr)