diff --git a/src/rt/circular_buffer.cpp b/src/rt/circular_buffer.cpp
index 77509abb069..8f12a1154a5 100644
--- a/src/rt/circular_buffer.cpp
+++ b/src/rt/circular_buffer.cpp
@@ -121,13 +121,15 @@ circular_buffer::dequeue(void *dst) {
     }
 
     // Shrink if possible.
-    if (_buffer_sz >= INITIAL_CIRCULAR_BUFFFER_SIZE_IN_UNITS * unit_sz &&
+    if (_buffer_sz > INITIAL_CIRCULAR_BUFFFER_SIZE_IN_UNITS * unit_sz &&
         _unread <= _buffer_sz / 4) {
         dom->log(rust_log::MEM | rust_log::COMM,
                  "circular_buffer is shrinking to %d bytes", _buffer_sz / 2);
         void *tmp = dom->malloc(_buffer_sz / 2);
         transfer(tmp);
         _buffer_sz >>= 1;
+	I(dom, _buffer_sz >=
+	  next_power_of_two(INITIAL_CIRCULAR_BUFFFER_SIZE_IN_UNITS * unit_sz));
         dom->free(_buffer);
         _buffer = (uint8_t *)tmp;
         _next = 0;
diff --git a/src/test/run-pass/chan-poweroftwo.rs b/src/test/run-pass/chan-poweroftwo.rs
index f3a4b9b5d66..da9a62cc9f8 100644
--- a/src/test/run-pass/chan-poweroftwo.rs
+++ b/src/test/run-pass/chan-poweroftwo.rs
@@ -38,9 +38,19 @@ impure fn test_grow() {
     }
 }
 
+// Don't allow the buffer to shrink below it's original size
+impure fn test_shrink() {
+    let port[i8] myport = port();
+    auto mychan = chan(myport);
+
+    mychan <| 0i8;
+    auto x <- myport;
+}
+
 impure fn main() {
     test_init();
     test_grow();
+    test_shrink();
 }
 
 // Local Variables: