diff --git a/Makefile b/Makefile
index 5ef44b222..d9d869a3b 100644
--- a/Makefile
+++ b/Makefile
@@ -104,6 +104,7 @@ coverage:
 HAS_GLIDE := $(shell command -v glide;)
 HAS_GOX := $(shell command -v gox;)
 HAS_GIT := $(shell command -v git;)
+HAS_HG := $(shell command -v hg;)
 
 .PHONY: bootstrap
 bootstrap:
@@ -116,6 +117,9 @@ endif
 
 ifndef HAS_GIT
 	$(error You must install Git)
+endif
+ifndef HAS_HG
+	$(error You must install Mercurial)
 endif
 	glide install --strip-vendor
 	go build -o bin/protoc-gen-go ./vendor/github.com/golang/protobuf/protoc-gen-go
diff --git a/docs/developers.md b/docs/developers.md
index ec17d2fa2..163ba1b9d 100644
--- a/docs/developers.md
+++ b/docs/developers.md
@@ -10,6 +10,8 @@ Helm and Tiller.
 - kubectl 1.2 or later
 - A Kubernetes cluster (optional)
 - The gRPC toolchain
+- Git
+- Mercurial
 
 ## Building Helm/Tiller