diff --git a/README b/README
index 0b170ad..5b9d986 100644
--- a/README
+++ b/README
@@ -18,9 +18,11 @@ Each line starts with a single word (command name), plus
 some command-specific parameters. Note that newlines are
 CRLF ("\r\n"), not just LF ("\n")!
 
-The following inputs are supported:
+The following inputs (in no particular order) are supported:
 
 	tick <ticknum>
+	BUMP
+		if received, the agent's move failed
 	DEAD
 		if received, the agent is dead!
 	energy <points>
diff --git a/connection.cc b/connection.cc
index 124df8d..80dba79 100644
--- a/connection.cc
+++ b/connection.cc
@@ -21,6 +21,14 @@ connection::senses(int tick_id, bool dead, int energy, char around[4])
 	pthread_mutex_unlock(&buf_lock);
 }
 
+void
+connection::bump(void)
+{
+	pthread_mutex_lock(&buf_lock);
+	out_buf.append("BUMP\n");
+	pthread_mutex_unlock(&buf_lock);
+}
+
 void
 connection::actions(class agent *agent)
 {
@@ -45,7 +53,8 @@ connection::actions(class agent *agent)
 			sscanf(line.c_str(), "%d %d", &x, &y);
 			if (x < -1) x = -1; if (x > 1) x = 1;
 			if (y < -1) y = -1; if (y > 1) y = 1;
-			agent->move_dir(x, y);
+			if (!agent->move_dir(x, y))
+				bump();
 		} else {
 			std::cout << "unknown line " << cmd << " " << line << " ...\n";
 		}
diff --git a/connection.h b/connection.h
index ff98597..518ce90 100644
--- a/connection.h
+++ b/connection.h
@@ -32,6 +32,8 @@ public:
 	void cancel(void);
 
 private:
+	void bump(void);
+
 	std::string out_buf, in_buf;
 	pthread_mutex_t buf_lock;