diff --git a/adb/commandline.cpp b/adb/commandline.cpp
index f193d2f..58e1ade 100644
--- a/adb/commandline.cpp
+++ b/adb/commandline.cpp
@@ -1457,27 +1457,27 @@
         return uninstall_app(ttype, serial, argc, argv);
     }
     else if (!strcmp(argv[0], "sync")) {
-        std::string src_arg;
+        std::string src;
         bool list_only = false;
         if (argc < 2) {
             // No local path was specified.
-            src_arg = "";
+            src = "";
         } else if (argc >= 2 && strcmp(argv[1], "-l") == 0) {
-            list_only = 1;
+            list_only = true;
             if (argc == 3) {
-                src_arg = argv[2];
+                src = argv[2];
             } else {
-                src_arg = "";
+                src = "";
             }
         } else if (argc == 2) {
             // A local path or "android"/"data" arg was specified.
-            src_arg = argv[1];
+            src = argv[1];
         } else {
             return usage();
         }
 
-        if (src_arg != "" &&
-            src_arg != "system" && src_arg != "data" && src_arg != "vendor" && src_arg != "oem") {
+        if (src != "" &&
+            src != "system" && src != "data" && src != "vendor" && src != "oem") {
             return usage();
         }
 
@@ -1485,25 +1485,19 @@
         std::string data_src_path = product_file("data");
         std::string vendor_src_path = product_file("vendor");
         std::string oem_src_path = product_file("oem");
-        if (!directory_exists(vendor_src_path)) {
-            vendor_src_path = "";
-        }
-        if (!directory_exists(oem_src_path)) {
-            oem_src_path = "";
-        }
 
         int rc = 0;
-        if (rc == 0 && (src_arg.empty() || src_arg == "system")) {
-            rc = do_sync_sync(system_src_path.c_str(), "/system", list_only);
+        if (rc == 0 && (src.empty() || src == "system")) {
+            rc = do_sync_sync(system_src_path, "/system", list_only);
         }
-        if (rc == 0 && (src_arg.empty() || src_arg == "vendor")) {
-            rc = do_sync_sync(vendor_src_path.c_str(), "/vendor", list_only);
+        if (rc == 0 && (src.empty() || src == "vendor") && directory_exists(vendor_src_path)) {
+            rc = do_sync_sync(vendor_src_path, "/vendor", list_only);
         }
-        if(rc == 0 && (src_arg.empty() || src_arg == "oem")) {
-            rc = do_sync_sync(oem_src_path.c_str(), "/oem", list_only);
+        if (rc == 0 && (src.empty() || src == "oem") && directory_exists(oem_src_path)) {
+            rc = do_sync_sync(oem_src_path, "/oem", list_only);
         }
-        if (rc == 0 && (src_arg.empty() || src_arg == "data")) {
-            rc = do_sync_sync(data_src_path.c_str(), "/data", list_only);
+        if (rc == 0 && (src.empty() || src == "data")) {
+            rc = do_sync_sync(data_src_path, "/data", list_only);
         }
         return rc;
     }
diff --git a/adb/file_sync_client.cpp b/adb/file_sync_client.cpp
index 730a5e2..49d8783 100644
--- a/adb/file_sync_client.cpp
+++ b/adb/file_sync_client.cpp
@@ -1027,18 +1027,18 @@
     }
 }
 
-int do_sync_sync(const char *lpath, const char *rpath, int listonly)
+int do_sync_sync(const std::string& lpath, const std::string& rpath, bool list_only)
 {
-    fprintf(stderr,"syncing %s...\n",rpath);
+    fprintf(stderr, "syncing %s...\n", rpath.c_str());
 
     int fd = adb_connect("sync:");
-    if(fd < 0) {
-        fprintf(stderr,"error: %s\n", adb_error());
+    if (fd < 0) {
+        fprintf(stderr, "error: %s\n", adb_error());
         return 1;
     }
 
     BEGIN();
-    if(copy_local_dir_remote(fd, lpath, rpath, 1, listonly)){
+    if (copy_local_dir_remote(fd, lpath.c_str(), rpath.c_str(), 1, list_only)) {
         return 1;
     } else {
         END();
diff --git a/adb/file_sync_service.h b/adb/file_sync_service.h
index 6e1ccce..344eb98 100644
--- a/adb/file_sync_service.h
+++ b/adb/file_sync_service.h
@@ -17,6 +17,8 @@
 #ifndef _FILE_SYNC_SERVICE_H_
 #define _FILE_SYNC_SERVICE_H_
 
+#include <string>
+
 #define htoll(x) (x)
 #define ltohl(x) (x)
 
@@ -67,7 +69,7 @@
 void file_sync_service(int fd, void *cookie);
 int do_sync_ls(const char *path);
 int do_sync_push(const char *lpath, const char *rpath, int show_progress);
-int do_sync_sync(const char *lpath, const char *rpath, int listonly);
+int do_sync_sync(const std::string& lpath, const std::string& rpath, bool list_only);
 int do_sync_pull(const char *rpath, const char *lpath, int show_progress, int pullTime);
 
 #define SYNC_DATA_MAX (64*1024)