diff --git a/tool/gocross/gocross-wrapper.sh b/tool/gocross/gocross-wrapper.sh
index 6a9104dd1..f91d7e235 100755
--- a/tool/gocross/gocross-wrapper.sh
+++ b/tool/gocross/gocross-wrapper.sh
@@ -90,7 +90,10 @@ fi
 # Anyway, build gocross in a stripped down universe.
 gocross_path="gocross"
 gocross_ok=0
-wantver="$(git rev-parse HEAD)"
+wantver="${GOCROSS_WANTVER:-}"
+if [[ "$wantver" == "" ]]; then
+    wantver="$(git rev-parse HEAD)"
+fi
 if [[ -x "$gocross_path" ]]; then
 	gotver="$($gocross_path gocross-version 2>/dev/null || echo '')"
 	if [[ "$gotver" == "$wantver" ]]; then
diff --git a/tool/gocross/toolchain.go b/tool/gocross/toolchain.go
index 5980dff04..203262d0e 100644
--- a/tool/gocross/toolchain.go
+++ b/tool/gocross/toolchain.go
@@ -15,6 +15,9 @@ import (
 )
 
 func toolchainRev() (string, error) {
+	if v := os.Getenv("GO_TOOLCHAIN_REV"); v != "" {
+		return v, nil
+	}
 	// gocross gets built in the root of the repo that has toolchain
 	// information, so we can use os.Args[0] to locate toolchain info.
 	//