diff --git a/README.md b/README.md
index 411716b82..2443697fa 100755
--- a/README.md
+++ b/README.md
@@ -215,6 +215,7 @@ Please select your language:
 
 ### V2 changes
 
+* v2.0, 2017-04-18, Fix [#848][bug #848], crash at HTTP fast buffer grow 2.0.239
 * v2.0, 2017-04-15, Fix [#844][bug #844], support Haivision encoder. 2.0.238
 * v2.0, 2017-04-15, Merge [#846][bug #846], fix fd leak for FLV stream caster. 2.0.237
 * v2.0, 2017-04-15, Merge [#841][bug #841], avoid the duplicated sps/pps in ts. 2.0.236
@@ -1394,6 +1395,7 @@ Winlin
 [bug #841]: https://github.com/ossrs/srs/issues/841
 [bug #846]: https://github.com/ossrs/srs/issues/846
 [bug #844]: https://github.com/ossrs/srs/issues/844
+[bug #848]: https://github.com/ossrs/srs/issues/848
 [bug #xxxxxxxxxx]: https://github.com/ossrs/srs/issues/xxxxxxxxxx
 
 [bug #735]: https://github.com/ossrs/srs/issues/735
diff --git a/trunk/src/protocol/srs_protocol_stream.cpp b/trunk/src/protocol/srs_protocol_stream.cpp
index 690441de0..32de59434 100755
--- a/trunk/src/protocol/srs_protocol_stream.cpp
+++ b/trunk/src/protocol/srs_protocol_stream.cpp
@@ -160,9 +160,10 @@ int SrsFastStream::grow(ISrsReader* reader, int required_size)
             // reset when buffer is empty.
             p = end = buffer;
             srs_verbose("all consumed, reset fast buffer");
-        } else {
+        } else if (nb_exists_bytes < nb_buffer && p > buffer) {
             // move the left bytes to start of buffer.
-            srs_assert(nb_exists_bytes < nb_buffer);
+            // @remark Only move memory when space is enough, or failed at next check.
+            // @see https://github.com/ossrs/srs/issues/848
             buffer = (char*)memmove(buffer, p, nb_exists_bytes);
             p = buffer;
             end = p + nb_exists_bytes;