diff --git a/src/google/protobuf/testing/zcgunzip.cc b/src/google/protobuf/testing/zcgunzip.cc
index 349ad86ee609b..d3403fd1e6413 100644
--- a/src/google/protobuf/testing/zcgunzip.cc
+++ b/src/google/protobuf/testing/zcgunzip.cc
@@ -42,6 +42,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <fcntl.h>
+#include <unistd.h>
 
 #ifdef _WIN32
 #ifndef STDIN_FILENO
diff --git a/src/google/protobuf/testing/zcgzip.cc b/src/google/protobuf/testing/zcgzip.cc
index 992ddc6ed66b3..4875755e37e6c 100644
--- a/src/google/protobuf/testing/zcgzip.cc
+++ b/src/google/protobuf/testing/zcgzip.cc
@@ -41,6 +41,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <fcntl.h>
+#include <unistd.h>
 
 #ifdef _WIN32
 #ifndef STDIN_FILENO