diff --git a/src/curl.cpp b/src/curl.cpp
index 4530af7..c1d0d56 100644
--- a/src/curl.cpp
+++ b/src/curl.cpp
@@ -2142,7 +2142,7 @@ bool S3fsCurl::GetResponseCode(long& responseCode, bool from_curl_handle) const
 //
 bool S3fsCurl::RemakeHandle()
 {
-    S3FS_PRN_INFO3("Retry request. [type=%d][url=%s][path=%s]", type, url.c_str(), path.c_str());
+    S3FS_PRN_INFO3("Retry request. [type=%d][url=%s][path=%s]", static_cast<int>(type), url.c_str(), path.c_str());
 
     if(REQTYPE::UNSET == type){
         return false;
@@ -2444,7 +2444,7 @@ bool S3fsCurl::RemakeHandle()
             break;
 
         default:
-            S3FS_PRN_ERR("request type is unknown(%d)", type);
+            S3FS_PRN_ERR("request type is unknown(%d)", static_cast<int>(type));
             return false;
     }
     if(!S3fsCurl::AddUserAgent(hCurl)){                            // put User-Agent
diff --git a/src/fdcache.cpp b/src/fdcache.cpp
index 8b79abc..b49f999 100644
--- a/src/fdcache.cpp
+++ b/src/fdcache.cpp
@@ -218,7 +218,8 @@ bool FdManager::MakeRandomTempPath(const char* path, std::string& tmppath)
 {
     char szBuff[64];
 
-    sprintf(szBuff, NOCACHE_PATH_PREFIX_FORM, random());     // worry for performance, but maybe don't worry.
+    snprintf(szBuff, sizeof(szBuff), NOCACHE_PATH_PREFIX_FORM, random());   // worry for performance, but maybe don't worry.
+    szBuff[sizeof(szBuff) - 1] = '\0';                                      // for safety
     tmppath  = szBuff;
     tmppath += path ? path : "";
     return true;
diff --git a/src/fdcache_entity.cpp b/src/fdcache_entity.cpp
index 9b4fa11..119be97 100644
--- a/src/fdcache_entity.cpp
+++ b/src/fdcache_entity.cpp
@@ -334,7 +334,8 @@ int FdEntity::OpenMirrorFile()
         // (do not care for threading, because allowed any value returned.)
         //
         char         szfile[NAME_MAX + 1];
-        sprintf(szfile, "%x.tmp", rand_r(&seed));
+        snprintf(szfile, sizeof(szfile), "%x.tmp", rand_r(&seed));
+        szfile[NAME_MAX] = '\0';                            // for safety
         mirrorpath = bupdir + "/" + szfile;
 
         // link mirror file to cache file
diff --git a/test/cr_filename.cc b/test/cr_filename.cc
index c77e399..411d078 100644
--- a/test/cr_filename.cc
+++ b/test/cr_filename.cc
@@ -41,7 +41,8 @@ int main(int argc, const char *argv[])
 
     int  fd;
     char filepath[4096];
-    sprintf(filepath, "%s\r", argv[1]);
+    snprintf(filepath, sizeof(filepath), "%s\r", argv[1]);
+    filepath[sizeof(filepath) - 1] = '\0';              // for safety
 
     // create empty file
     if(-1 == (fd = open(filepath, O_CREAT|O_RDWR, 0644))){
diff --git a/test/mknod_test.cc b/test/mknod_test.cc
index f5bc240..fc7137f 100644
--- a/test/mknod_test.cc
+++ b/test/mknod_test.cc
@@ -73,27 +73,31 @@ bool TestMknod(const char* basepath, mode_t mode)
         case S_IFREG:
             str_mode = str_mode_reg;
             dev      = 0;
-            sprintf(filepath, "%s.%s", basepath, str_ext_reg);
+            snprintf(filepath, sizeof(filepath), "%s.%s", basepath, str_ext_reg);
+            filepath[S3FS_TEST_PATH_MAX - 1] = '\0';    // for safety
             break;
         case S_IFCHR:
             str_mode = str_mode_chr;
             dev      = makedev(0, 0);
-            sprintf(filepath, "%s.%s", basepath, str_ext_chr);
+            snprintf(filepath, sizeof(filepath), "%s.%s", basepath, str_ext_chr);
+            filepath[S3FS_TEST_PATH_MAX - 1] = '\0';    // for safety
             break;
         case S_IFBLK:
             str_mode = str_mode_blk;
-            dev      = makedev((unsigned int)(259), 0);     // temporary value
-            sprintf(filepath, "%s.%s", basepath, str_ext_blk);
+            dev      = makedev((unsigned int)(259), 0); // temporary value
+            snprintf(filepath, sizeof(filepath), "%s.%s", basepath, str_ext_blk);
+            filepath[S3FS_TEST_PATH_MAX - 1] = '\0';    // for safety
             break;
         case S_IFIFO:
             str_mode = str_mode_fifo;
             dev      = 0;
-            sprintf(filepath, "%s.%s", basepath, str_ext_fifo);
+            snprintf(filepath, sizeof(filepath), "%s.%s", basepath, str_ext_fifo);
+            filepath[S3FS_TEST_PATH_MAX - 1] = '\0';    // for safety
             break;
         case S_IFSOCK:
             str_mode = str_mode_sock;
             dev      = 0;
-            snprintf(filepath, S3FS_TEST_PATH_MAX, "%s.%s", basepath, str_ext_sock);
+            snprintf(filepath, sizeof(filepath), "%s.%s", basepath, str_ext_sock);
             filepath[S3FS_TEST_PATH_MAX - 1] = '\0';    // for safety
             break;
         default:
diff --git a/test/truncate_read_file.cc b/test/truncate_read_file.cc
index 2959439..1995b50 100644
--- a/test/truncate_read_file.cc
+++ b/test/truncate_read_file.cc
@@ -58,7 +58,8 @@ int main(int argc, char *argv[])
 
     // run sub-process for reading file(cat)
     char szCommand[1024];
-    sprintf(szCommand, "cat %s >/dev/null 2>&1", filepath);
+    snprintf(szCommand, sizeof(szCommand), "cat %s >/dev/null 2>&1", filepath);
+    szCommand[sizeof(szCommand) - 1] = '\0';                    // for safety
     if(0 != system(szCommand)){
         fprintf(stderr, "[ERROR] Failed to run sub-process(cat).\n");
         close(fd);