diff --git a/libc/bionic/libc_logging.cpp b/libc/bionic/libc_logging.cpp
index 6802944..517d047 100644
--- a/libc/bionic/libc_logging.cpp
+++ b/libc/bionic/libc_logging.cpp
@@ -107,7 +107,7 @@
 
 struct FdOutputStream {
  public:
-  FdOutputStream(int fd) : total(0), fd_(fd) {
+  explicit FdOutputStream(int fd) : total(0), fd_(fd) {
   }
 
   void Send(const char* data, int len) {