diff --git a/targets.cc b/targets.cc
index 1dd199046..b0fdacaf2 100644
--- a/targets.cc
+++ b/targets.cc
@@ -401,9 +401,10 @@ HostGroupState::~HostGroupState() {
   free(hostbatch);
 }
 
+/* Returns true iff the defer buffer is not yet full. */
 bool HostGroupState::defer(Target *t) {
   this->defer_buffer.push_back(t);
-  return true;
+  return this->defer_buffer.size() < HostGroupState::DEFER_LIMIT;
 }
 
 void HostGroupState::undefer() {
diff --git a/targets.h b/targets.h
index d65700fd6..97992a00c 100644
--- a/targets.h
+++ b/targets.h
@@ -157,6 +157,9 @@ public:
 
 class HostGroupState {
 public:
+  /* The maximum number of entries we want to allow storing in defer_buffer. */
+  static const unsigned int DEFER_LIMIT = 64;
+
   HostGroupState(int lookahead, int randomize, int argc, const char *argv[]);
   ~HostGroupState();
   Target **hostbatch;
@@ -180,6 +183,7 @@ public:
 		    at a time to the client program */
   TargetGroup current_group; /* For batch chunking -- targets in queue */
 
+  /* Returns true iff the defer buffer is not yet full. */
   bool defer(Target *t);
   void undefer();
   const char *next_expression();