diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index 3e890c717..271ca9527 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -53,6 +53,7 @@
 #include <android-base/parsenetaddress.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
+#include <android-base/test_utils.h>
 #include <android-base/unique_fd.h>
 #include <sparse/sparse.h>
 #include <ziparchive/zip_archive.h>
@@ -1350,7 +1351,8 @@ static void fb_perform_format(Transport* transport,
     struct fastboot_buffer buf;
     const char* errMsg = nullptr;
     const struct fs_generator* gen = nullptr;
-    int fd;
+    TemporaryFile output;
+    unique_fd fd;
 
     unsigned int limit = INT_MAX;
     if (target_sparse_limit > 0 && target_sparse_limit < limit) {
@@ -1403,22 +1405,23 @@ static void fb_perform_format(Transport* transport,
         return;
     }
 
-    fd = make_temporary_fd();
-    if (fd == -1) return;
-
     unsigned eraseBlkSize, logicalBlkSize;
     eraseBlkSize = fb_get_flash_block_size(transport, "erase-block-size");
     logicalBlkSize = fb_get_flash_block_size(transport, "logical-block-size");
 
-    if (fs_generator_generate(gen, fd, size, initial_dir, eraseBlkSize, logicalBlkSize)) {
+    if (fs_generator_generate(gen, output.path, size, initial_dir,
+            eraseBlkSize, logicalBlkSize)) {
         fprintf(stderr, "Cannot generate image: %s\n", strerror(errno));
-        close(fd);
         return;
     }
 
-    if (!load_buf_fd(transport, fd, &buf)) {
+    fd.reset(open(output.path, O_RDONLY));
+    if (fd == -1) {
+        fprintf(stderr, "Cannot open generated image: %s\n", strerror(errno));
+        return;
+    }
+    if (!load_buf_fd(transport, fd.release(), &buf)) {
         fprintf(stderr, "Cannot read image: %s\n", strerror(errno));
-        close(fd);
         return;
     }
     flash_buf(partition, &buf);
diff --git a/fastboot/fs.cpp b/fastboot/fs.cpp
index 5d9ccfe09..99ca7dd81 100644
--- a/fastboot/fs.cpp
+++ b/fastboot/fs.cpp
@@ -4,6 +4,7 @@
 #include "make_f2fs.h"
 
 #include <errno.h>
+#include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -11,12 +12,20 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+#include <android-base/unique_fd.h>
 #include <ext4_utils/make_ext4fs.h>
 #include <sparse/sparse.h>
 
-static int generate_ext4_image(int fd, long long partSize, const std::string& initial_dir,
+using android::base::unique_fd;
+
+static int generate_ext4_image(const char* fileName, long long partSize, const std::string& initial_dir,
                                        unsigned eraseBlkSize, unsigned logicalBlkSize)
 {
+    unique_fd fd(open(fileName, O_CREAT | O_RDWR | O_TRUNC, S_IRUSR | S_IWUSR));
+    if (fd == -1) {
+        fprintf(stderr, "Unable to open output file for EXT4 filesystem: %s\n", strerror(errno));
+        return -1;
+    }
     if (initial_dir.empty()) {
         make_ext4fs_sparse_fd_align(fd, partSize, NULL, NULL, eraseBlkSize, logicalBlkSize);
     } else {
@@ -27,11 +36,16 @@ static int generate_ext4_image(int fd, long long partSize, const std::string& in
 }
 
 #ifdef USE_F2FS
-static int generate_f2fs_image(int fd, long long partSize, const std::string& initial_dir,
+static int generate_f2fs_image(const char* fileName, long long partSize, const std::string& initial_dir,
                                unsigned /* unused */, unsigned /* unused */)
 {
     if (!initial_dir.empty()) {
-        fprintf(stderr, "Unable to set initial directory on F2FS filesystem\n");
+        fprintf(stderr, "Unable to set initial directory on F2FS filesystem: %s\n", strerror(errno));
+        return -1;
+    }
+    unique_fd fd(open(fileName, O_CREAT | O_RDWR | O_TRUNC, S_IRUSR | S_IWUSR));
+    if (fd == -1) {
+        fprintf(stderr, "Unable to open output file for F2FS filesystem: %s\n", strerror(errno));
         return -1;
     }
     return make_f2fs_sparse_fd(fd, partSize, NULL, NULL);
@@ -42,7 +56,7 @@ static const struct fs_generator {
     const char* fs_type;  //must match what fastboot reports for partition type
 
     //returns 0 or error value
-    int (*generate)(int fd, long long partSize, const std::string& initial_dir,
+    int (*generate)(const char* fileName, long long partSize, const std::string& initial_dir,
                     unsigned eraseBlkSize, unsigned logicalBlkSize);
 
 } generators[] = {
@@ -61,8 +75,8 @@ const struct fs_generator* fs_get_generator(const std::string& fs_type) {
     return nullptr;
 }
 
-int fs_generator_generate(const struct fs_generator* gen, int tmpFileNo, long long partSize,
+int fs_generator_generate(const struct fs_generator* gen, const char* fileName, long long partSize,
     const std::string& initial_dir, unsigned eraseBlkSize, unsigned logicalBlkSize)
 {
-    return gen->generate(tmpFileNo, partSize, initial_dir, eraseBlkSize, logicalBlkSize);
+    return gen->generate(fileName, partSize, initial_dir, eraseBlkSize, logicalBlkSize);
 }
diff --git a/fastboot/fs.h b/fastboot/fs.h
index 0a5f5a4d7..c6baa7f67 100644
--- a/fastboot/fs.h
+++ b/fastboot/fs.h
@@ -7,7 +7,7 @@
 struct fs_generator;
 
 const struct fs_generator* fs_get_generator(const std::string& fs_type);
-int fs_generator_generate(const struct fs_generator* gen, int tmpFileNo, long long partSize,
+int fs_generator_generate(const struct fs_generator* gen, const char* fileName, long long partSize,
     const std::string& initial_dir, unsigned eraseBlkSize = 0, unsigned logicalBlkSize = 0);
 
 #endif