diff --git a/src/include/piomatter/piomatter.h b/src/include/piomatter/piomatter.h
index c43f7ec..1143a18 100644
--- a/src/include/piomatter/piomatter.h
+++ b/src/include/piomatter/piomatter.h
@@ -26,7 +26,7 @@ struct piomatter_base {
     piomatter_base &operator=(const piomatter_base &) = delete;
 
     virtual ~piomatter_base() {}
-    virtual void show() = 0;
+    virtual int show() = 0;
 
     double fps;
 };
@@ -48,7 +48,11 @@ struct piomatter : piomatter_base {
         show();
     }
 
-    void show() override {
+    int show() override {
+        int err = pending_error_errno.exchange(0); // we're handling this error
+        if (err != 0) {
+            return err;
+        }
         int buffer_idx = manager.get_free_buffer();
         auto &bufseq = buffers[buffer_idx];
         bufseq.resize(geometry.schedules.size());
@@ -61,6 +65,7 @@ struct piomatter : piomatter_base {
             old_active_time = geometry.schedules[i].back().active_time;
         }
         manager.put_filled_buffer(buffer_idx);
+        return 0;
     }
 
     ~piomatter() {
@@ -174,7 +179,15 @@ struct piomatter : piomatter_base {
                 const auto &data = cur_buf[seq_idx];
                 auto datasize = sizeof(uint32_t) * data.size();
                 auto dataptr = const_cast<uint32_t *>(&data[0]);
-                pio_sm_xfer_data(pio, sm, PIO_DIR_TO_SM, datasize, dataptr);
+                // returns err = rp1_ioctl.... which seems to be a negative
+                // errno value
+                int r =
+                    pio_sm_xfer_data(pio, sm, PIO_DIR_TO_SM, datasize, dataptr);
+                if (r != 0) {
+                    pending_error_errno.store(-r);
+                    printf("xfer_data() returned error %d (%s)\n", r,
+                           strerror(-r));
+                }
                 t1 = monotonicns64();
                 if (t0 != t1) {
                     fps = 1e9 / (t1 - t0);
@@ -194,6 +207,7 @@ struct piomatter : piomatter_base {
     matrix_geometry geometry;
     colorspace converter;
     std::thread blitter_thread;
+    std::atomic<int> pending_error_errno;
 };
 
 } // namespace piomatter
diff --git a/src/pymain.cpp b/src/pymain.cpp
index 483b2dc..053aded 100644
--- a/src/pymain.cpp
+++ b/src/pymain.cpp
@@ -18,7 +18,14 @@ struct PyPiomatter {
     py::buffer buffer;
     std::unique_ptr<piomatter::piomatter_base> matter;
 
-    void show() { matter->show(); }
+    void show() {
+        int err = matter->show();
+        if (err != 0) {
+            errno = err;
+            PyErr_SetFromErrno(PyExc_OSError);
+            throw py::error_already_set();
+        }
+    }
     double fps() const { return matter->fps; }
 };