diff --git a/CMakeLists.txt b/CMakeLists.txt
index f17afb8a3..2a1900862 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,6 +6,7 @@ SET(CMAKE_PROJECT_HOMEPAGE_URL "http://gmssl.org")
 set(LIBRARY_OUTPUT_PATH ${PROJECT_BINARY_DIR}/bin)
 set(EXECUTABLE_OUTPUT_PATH ${PROJECT_BINARY_DIR}/bin)
 SET(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH};${CMAKE_CURRENT_SOURCE_DIR}/cmake")
+SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
 
 include_directories(include)
 
diff --git a/tools/tlcp_client.c b/tools/tlcp_client.c
index 6380ad4c7..93717ac3c 100644
--- a/tools/tlcp_client.c
+++ b/tools/tlcp_client.c
@@ -15,6 +15,9 @@
 #include <gmssl/tls.h>
 #include <gmssl/x509.h>
 #include <gmssl/error.h>
+#ifndef WIN32
+	#include <sys/select.h>
+#endif
 
 
 #define TIMEOUT_SECONDS 1
diff --git a/tools/tls12_client.c b/tools/tls12_client.c
index af51ed8f1..5645bdeb5 100644
--- a/tools/tls12_client.c
+++ b/tools/tls12_client.c
@@ -14,6 +14,9 @@
 #include <stdlib.h>
 #include <gmssl/tls.h>
 #include <gmssl/error.h>
+#ifndef WIN32
+	#include <sys/select.h>
+#endif
 
 
 // TLSv1.2客户单和TLCP客户端可能没有什么区别
diff --git a/tools/tls13_client.c b/tools/tls13_client.c
index 03d63e77a..f2f9b1c44 100644
--- a/tools/tls13_client.c
+++ b/tools/tls13_client.c
@@ -14,6 +14,9 @@
 #include <stdlib.h>
 #include <gmssl/tls.h>
 #include <gmssl/error.h>
+#ifndef WIN32
+	#include <sys/select.h>
+#endif
 
 
 // TLSv1.2客户单和TLCP客户端可能没有什么区别