diff --git a/config/Tools.mk.in b/config/Tools.mk.in
index 1e5cc20bf7..98245f63c9 100644
--- a/config/Tools.mk.in
+++ b/config/Tools.mk.in
@@ -40,8 +40,8 @@ XEN_TOOLS_RPATH     := @rpath@
 # Download GIT repositories via HTTP or GIT's own protocol?
 # GIT's protocol is faster and more robust, when it works at all (firewalls
 # may block it). We make it the default, but if your GIT repository downloads
-# fail or hang, please specify GIT_HTTP=y in your environment.
-GIT_HTTP            := @githttp@
+# fail or hang, please pass --enable-githttp to configure.
+GIT_HTTP            ?= @githttp@
 
 # Optional components
 XENSTAT_XENTOP      := @monitors@
diff --git a/config/Toplevel.mk.in b/config/Toplevel.mk.in
index 1d991895ea..4ecacbb37d 100644
--- a/config/Toplevel.mk.in
+++ b/config/Toplevel.mk.in
@@ -1,2 +1,2 @@
 SUBSYSTEMS               := @SUBSYSTEMS@
-GIT_HTTP                 := @githttp@
+GIT_HTTP                 ?= @githttp@