diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index bc04c8adb..66e525642 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -216,6 +216,7 @@ bool RemoteStore::hasSubstitutes(const Path & path)
 bool RemoteStore::querySubstitutablePathInfo(const Path & path,
     SubstitutablePathInfo & info)
 {
+    if (GET_PROTOCOL_MINOR(daemonVersion) < 3) return false;
     writeInt(wopQuerySubstitutablePathInfo, to);
     writeString(path, to);
     processStderr();
diff --git a/src/libstore/worker-protocol.hh b/src/libstore/worker-protocol.hh
index 1146f9577..63e3f0eb8 100644
--- a/src/libstore/worker-protocol.hh
+++ b/src/libstore/worker-protocol.hh
@@ -8,7 +8,7 @@ namespace nix {
 #define WORKER_MAGIC_1 0x6e697863
 #define WORKER_MAGIC_2 0x6478696f
 
-#define PROTOCOL_VERSION 0x102
+#define PROTOCOL_VERSION 0x103
 #define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
 #define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)