diff --git a/nengo_loihi/simulator.py b/nengo_loihi/simulator.py
index b9de67c39..cebbbf038 100644
--- a/nengo_loihi/simulator.py
+++ b/nengo_loihi/simulator.py
@@ -83,6 +83,7 @@ class Simulator(object):
     def __init__(self, network, dt=0.001, seed=None, model=None,  # noqa: C901
                  precompute=True, target=None):
         self.closed = True  # Start closed in case constructor raises exception
+        self.running = False
 
         if model is None:
             # Call the builder to make a model
@@ -229,8 +230,21 @@ def close(self):
         `.Simulator.step`, and `.Simulator.reset` on a closed simulator raises
         a `.SimulatorClosed` exception.
         """
+        if self.closed:
+            return
         self.closed = True
         self.signals = None  # signals may no longer exist on some backends
+        if self.loihi is not None:
+            if not self.precompute and self.running:
+                print('send a stop signal to the snip')
+                self.loihi.nengo_io_h2c.write(1, [-1])
+                import time
+                time.sleep(0.5)  # need to wait for stop signal to arrive
+                print('closing loihi...')
+                # this takes a while, since loihi seems to need to finish
+                #  all of the steps its been told to do
+                self.loihi.close()
+                print('...closed')
 
     def _probe(self):
         """Copy all probed signals to buffers."""
@@ -316,10 +330,11 @@ def step(self):
 
         self.run_steps(1)
 
-    def run_steps(self, steps):
+    def run_steps(self, steps):  # noqa: C901
         if self.closed:
             raise SimulatorClosed("Simulator cannot run because it is closed.")
 
+        self.running = True
         if self.simulator is not None:
             if self.precompute:
                 self.host_pre_sim.run_steps(steps)
@@ -327,14 +342,19 @@ def run_steps(self, steps):
                 self.simulator.run_steps(steps)
                 self.handle_chip2host_communications()
                 self.host_post_sim.run_steps(steps)
+                self._n_steps += steps
             elif self.host_sim is None:
                 self.simulator.run_steps(steps)
+                self._n_steps += steps
             else:
                 for i in range(steps):
+                    if self.closed:
+                        break
                     self.host_sim.step()
                     self.handle_host2chip_communications()
                     self.simulator.step()
                     self.handle_chip2host_communications()
+                    self._n_steps += 1
         elif self.loihi is not None:
             if self.precompute:
                 self.host_pre_sim.run_steps(steps)
@@ -342,22 +362,35 @@ def run_steps(self, steps):
                 self.loihi.run_steps(steps)
                 self.handle_chip2host_communications()
                 self.host_post_sim.run_steps(steps)
+                self._n_steps += steps
             elif self.host_sim is not None:
                 self.loihi.create_io_snip()
-                self.loihi.run_steps(steps, async=True)
-                for i in range(steps):
-                    self.host_sim.run_steps(1)
-                    self.handle_host2chip_communications()
-                    self.handle_chip2host_communications()
-
-                print('Waiting for completion')
-                self.loihi.nengo_io_h2c.write(1, [0])
-                self.loihi.wait_for_completion()
-                print("done")
+                try:
+                    self.loihi.run_steps(steps, async=True)
+                    for i in range(steps):
+                        if self.closed:
+                            break
+                        self.host_sim.run_steps(1)
+                        self.handle_host2chip_communications()
+                        self.handle_chip2host_communications()
+                        self._n_steps += 1
+                except KeyboardInterrupt:
+                    # tell the snip to shut down
+                    self.loihi.nengo_io_h2c.write(1, [-1])
+                    raise
+                finally:
+                    try:
+                        # tell the snip to shut down
+                        self.loihi.nengo_io_h2c.write(1, [-1])
+                        self.loihi.wait_for_completion()
+                    except EOFError:
+                        # it has already been shut down
+                        pass
             else:
                 self.loihi.run_steps(steps)
+                self._n_steps += steps
 
-        self._n_steps += steps
+        self.running = False
         self._probe()
 
     def handle_host2chip_communications(self):  # noqa: C901
diff --git a/nengo_loihi/snips/nengo_io.c.template b/nengo_loihi/snips/nengo_io.c.template
index 4a28593fd..1809c71ec 100644
--- a/nengo_loihi/snips/nengo_io.c.template
+++ b/nengo_loihi/snips/nengo_io.c.template
@@ -5,9 +5,20 @@
 #define N_OUTPUTS %d
 
 void nengo_io(runState *s) {
+    // use the last element in userData as a quit flag
+    if (s->userData[1023] != 0) {
+        return;
+    }
+
     int count[1];
     readChannel("nengo_io_h2c", count, 1);
     //printf("count %%d\n", count[0]);
+    if (count[0] < 0) {
+        // a negative value indicates we should stop
+        s->userData[1023] = 1;
+        printf("stopping\n");
+        return;
+    }
 
     int spike[2];
     for (int i=0; i<count[0]; i++) {
diff --git a/nengo_loihi/tests/test_stopping.py b/nengo_loihi/tests/test_stopping.py
new file mode 100644
index 000000000..4fb1bea2f
--- /dev/null
+++ b/nengo_loihi/tests/test_stopping.py
@@ -0,0 +1,39 @@
+import nengo
+import pytest
+
+
+def test_stopping(Simulator, seed):
+    model = nengo.Network(seed=seed)
+    with model:
+        stim = nengo.Node(0.5)
+        ens = nengo.Ensemble(n_neurons=100, dimensions=1)
+        nengo.Connection(stim, ens)
+
+        def output_func(t, x):
+            if t > 0.05:
+                raise Exception('Stopping')
+        output = nengo.Node(output_func, size_in=1)
+        nengo.Connection(ens, output)
+
+    with Simulator(model, precompute=False) as sim:
+        with pytest.raises(Exception):
+            sim.run(0.1)
+
+
+def test_closing(Simulator, seed):
+    model = nengo.Network(seed=seed)
+    with model:
+        stim = nengo.Node(0.5)
+        ens = nengo.Ensemble(n_neurons=100, dimensions=1)
+        nengo.Connection(stim, ens)
+
+        def output_func(t, x):
+            if t > 0.05:
+                sim.close()
+        output = nengo.Node(output_func, size_in=1)
+        nengo.Connection(ens, output)
+
+    sim = Simulator(model, precompute=False)
+
+    sim.run(0.1)
+    assert sim.n_steps == 51