diff --git a/README.md b/README.md
index 2360de420..1e778e66e 100755
--- a/README.md
+++ b/README.md
@@ -155,6 +155,8 @@ For previous versions, please read:
 
 ## V4 changes
 
+* v4.0, 2021-02-04, At least wait 1ms when <1ms, to avoid epoll_wait spin loop. 4.0.66
+* v4.0, 2021-01-31, Enable -std=c++11 by default. 4.0.65
 * v4.0, 2021-01-25, Enable --nasm and --srtp-asm by default for performance. 4.0.64
 * v4.0, 2021-01-20, Support HTTP-FLV and HLS for srs-player by H5. 4.0.63
 * v4.0, 2021-01-08, HTML5 video tag resolution adaptive. 4.0.59
diff --git a/trunk/3rdparty/st-srs/event.c b/trunk/3rdparty/st-srs/event.c
index 142882a51..5b640c104 100644
--- a/trunk/3rdparty/st-srs/event.c
+++ b/trunk/3rdparty/st-srs/event.c
@@ -1210,6 +1210,11 @@ ST_HIDDEN void _st_epoll_dispatch(void)
     } else {
         min_timeout = (_ST_SLEEPQ->due <= _ST_LAST_CLOCK) ? 0 : (_ST_SLEEPQ->due - _ST_LAST_CLOCK);
         timeout = (int) (min_timeout / 1000);
+
+        // At least wait 1ms when <1ms, to avoid epoll_wait spin loop.
+        if (min_timeout > 0 && timeout == 0) {
+            timeout = 1;
+        }
     }
 
     if (_st_epoll_data->pid != getpid()) {
diff --git a/trunk/src/core/srs_core_version4.hpp b/trunk/src/core/srs_core_version4.hpp
index c50b667a2..916b6e361 100644
--- a/trunk/src/core/srs_core_version4.hpp
+++ b/trunk/src/core/srs_core_version4.hpp
@@ -24,6 +24,6 @@
 #ifndef SRS_CORE_VERSION4_HPP
 #define SRS_CORE_VERSION4_HPP
 
-#define SRS_VERSION4_REVISION 65
+#define SRS_VERSION4_REVISION 66
 
 #endif