diff --git a/common/libs/fs/shared_fd.cpp b/common/libs/fs/shared_fd.cpp
index dde0604..6db27ee 100644
--- a/common/libs/fs/shared_fd.cpp
+++ b/common/libs/fs/shared_fd.cpp
@@ -23,6 +23,7 @@
 #include <netinet/in.h>
 #include <unistd.h>
 #include <algorithm>
+#include <vector>
 
 #include "common/libs/auto_resources/auto_resources.h"
 #include "common/libs/glog/logging.h"
@@ -57,8 +58,7 @@
 namespace cvd {
 
 bool FileInstance::CopyFrom(FileInstance& in) {
-  AutoFreeBuffer buffer;
-  buffer.Resize(8192);
+  std::vector<char> buffer(8192);
   while (true) {
     ssize_t num_read = in.Read(buffer.data(), buffer.size());
     if (!num_read) {
@@ -78,8 +78,7 @@
 }
 
 bool FileInstance::CopyFrom(FileInstance& in, size_t length) {
-  AutoFreeBuffer buffer;
-  buffer.Resize(8192);
+  std::vector<char> buffer(8192);
   while (length > 0) {
     ssize_t num_read = in.Read(buffer.data(), std::min(buffer.size(), length));
     length -= num_read;
@@ -95,30 +94,34 @@
 }
 
 void FileInstance::Close() {
-  AutoFreeBuffer message;
+  std::stringstream message;
   if (fd_ == -1) {
     errno_ = EBADF;
   } else if (close(fd_) == -1) {
     errno_ = errno;
     if (identity_.size()) {
-      message.PrintF("%s: %s failed (%s)", __FUNCTION__, identity_.data(),
-                     StrError());
-      Log(message.data());
+      message << __FUNCTION__ << ": " << identity_ << " failed (" << StrError() << ")";
+      std::string message_str = message.str();
+      Log(message_str.c_str());
     }
   } else {
     if (identity_.size()) {
-      message.PrintF("%s: %s succeeded", __FUNCTION__, identity_.data());
-      Log(message.data());
+      message << __FUNCTION__ << ": " << identity_ << "succeeded";
+      std::string message_str = message.str();
+      Log(message_str.c_str());
     }
   }
   fd_ = -1;
 }
 
 void FileInstance::Identify(const char* identity) {
-  identity_.PrintF("fd=%d @%p is %s", fd_, this, identity);
-  AutoFreeBuffer message;
-  message.PrintF("%s: %s", __FUNCTION__, identity_.data());
-  Log(message.data());
+  std::stringstream identity_stream;
+  identity_stream << "fd=" << fd_ << " @" << this << " is " << identity;
+  identity_ = identity_stream.str();
+  std::stringstream message;
+  message << __FUNCTION__ << ": " << identity_;
+  std::string message_str = message.str();
+  Log(message_str.c_str());
 }
 
 bool FileInstance::IsSet(fd_set* in) const {
diff --git a/common/libs/fs/shared_fd.h b/common/libs/fs/shared_fd.h
index b811f4a..b64ad09 100644
--- a/common/libs/fs/shared_fd.h
+++ b/common/libs/fs/shared_fd.h
@@ -33,6 +33,7 @@
 #include <sys/un.h>
 
 #include <memory>
+#include <sstream>
 
 #include <errno.h>
 #include <fcntl.h>
@@ -515,7 +516,9 @@
     // Ensure every file descriptor managed by a FileInstance has the CLOEXEC
     // flag
     TEMP_FAILURE_RETRY(fcntl(fd, F_SETFD, FD_CLOEXEC));
-    identity_.PrintF("fd=%d @%p", fd, this);
+    std::stringstream identity;
+    identity << "fd=" << fd << " @" << this;
+    identity_ = identity.str();
   }
 
   FileInstance* Accept(struct sockaddr* addr, socklen_t* addrlen) const {
@@ -529,7 +532,7 @@
 
   int fd_;
   int errno_;
-  AutoFreeBuffer identity_;
+  std::string identity_;
   char strerror_buf_[160];
 };