diff --git a/src/metaheader.cpp b/src/metaheader.cpp
index 69e97e8..90a4895 100644
--- a/src/metaheader.cpp
+++ b/src/metaheader.cpp
@@ -19,6 +19,8 @@
  */
 
 #include <ctime>
+#include <iomanip>
+#include <sstream>
 #include <unistd.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -254,8 +256,8 @@ time_t cvtIAMExpireStringToTime(const char* s)
     if(!s){
         return 0L;
     }
-    memset(&tm, 0, sizeof(struct tm));
-    strptime(s, "%Y-%m-%dT%H:%M:%S", &tm);
+    std::istringstream ss(s);
+    ss >> std::get_time(&tm, "%Y-%m-%dT%H:%M:%S");
     return timegm(&tm); // GMT
 }
 
@@ -265,8 +267,8 @@ time_t get_lastmodified(const char* s)
     if(!s){
         return -1;
     }
-    memset(&tm, 0, sizeof(struct tm));
-    strptime(s, "%a, %d %b %Y %H:%M:%S %Z", &tm);
+    std::istringstream ss(s);
+    ss >> std::get_time(&tm, "%a, %d %b %Y %H:%M:%S %Z");
     return timegm(&tm); // GMT
 }
 
diff --git a/src/s3fs_logger.cpp b/src/s3fs_logger.cpp
index 12b93cb..ddee301 100644
--- a/src/s3fs_logger.cpp
+++ b/src/s3fs_logger.cpp
@@ -54,15 +54,14 @@ std::string S3fsLog::GetCurrentTime()
         struct timeval  now;
         struct timespec tsnow;
         struct tm res;
-        char   tmp[32];
         if(-1 == clock_gettime(S3FS_CLOCK_MONOTONIC, &tsnow)){
             now.tv_sec  = tsnow.tv_sec;
             now.tv_usec = (tsnow.tv_nsec / 1000);
         }else{
             gettimeofday(&now, nullptr);
         }
-        strftime(tmp, sizeof(tmp), "%Y-%m-%dT%H:%M:%S", gmtime_r(&now.tv_sec, &res));
-        current_time << tmp << "." << std::setfill('0') << std::setw(3) << (now.tv_usec / 1000) << "Z ";
+        current_time << std::put_time(gmtime_r(&now.tv_sec, &res), "%Y-%m-%dT%H:%M:%S")
+                     << "." << std::setfill('0') << std::setw(3) << (now.tv_usec / 1000) << "Z ";
     }
     return current_time.str();
 }
diff --git a/src/string_util.cpp b/src/string_util.cpp
index a1ab4cd..235f912 100644
--- a/src/string_util.cpp
+++ b/src/string_util.cpp
@@ -23,7 +23,6 @@
 #include <cerrno>
 #include <climits>
 #include <iomanip>
-
 #include <sstream>
 
 #include "s3fs_logger.h"
@@ -47,24 +46,6 @@ std::string str(const struct timespec value)
     return s.str();
 }
 
-#ifdef __MSYS__
-/*
- * Polyfill for strptime function
- *
- * This source code is from https://gist.github.com/jeremyfromearth/5694aa3a66714254752179ecf3c95582 .
- */
-char* strptime(const char* s, const char* f, struct tm* tm)
-{
-    std::istringstream input(s);
-    input.imbue(std::locale(setlocale(LC_ALL, nullptr)));
-    input >> std::get_time(tm, f);
-    if (input.fail()) {
-        return nullptr;
-    }
-    return (char*)(s + input.tellg());
-}
-#endif
-
 bool s3fs_strtoofft(off_t* value, const char* str, int base)
 {
     if(value == nullptr || str == nullptr){
@@ -259,11 +240,11 @@ bool get_keyword_value(const std::string& target, const char* keyword, std::stri
 //
 std::string get_date_rfc850()
 {
-    char buf[100];
+    std::ostringstream ss;
     time_t t = time(nullptr);
     struct tm res;
-    strftime(buf, sizeof(buf), "%a, %d %b %Y %H:%M:%S GMT", gmtime_r(&t, &res));
-    return buf;
+    ss << std::put_time(gmtime_r(&t, &res), "%a, %d %b %Y %H:%M:%S GMT");
+    return ss.str();
 }
 
 void get_date_sigv3(std::string& date, std::string& date8601)
@@ -275,18 +256,18 @@ void get_date_sigv3(std::string& date, std::string& date8601)
 
 std::string get_date_string(time_t tm)
 {
-    char buf[100];
+    std::ostringstream ss;
     struct tm res;
-    strftime(buf, sizeof(buf), "%Y%m%d", gmtime_r(&tm, &res));
-    return buf;
+    ss << std::put_time(gmtime_r(&tm, &res), "%Y%m%d");
+    return ss.str();
 }
 
 std::string get_date_iso8601(time_t tm)
 {
-    char buf[100];
+    std::ostringstream s;
     struct tm res;
-    strftime(buf, sizeof(buf), "%Y%m%dT%H%M%SZ", gmtime_r(&tm, &res));
-    return buf;
+    s << std::put_time(gmtime_r(&tm, &res), "%Y%m%dT%H%M%SZ");
+    return s.str();
 }
 
 bool get_unixtime_from_iso8601(const char* pdate, time_t& unixtime)
@@ -296,8 +277,9 @@ bool get_unixtime_from_iso8601(const char* pdate, time_t& unixtime)
     }
 
     struct tm tm;
-    const char* prest = strptime(pdate, "%Y-%m-%dT%T", &tm);
-    if(prest == pdate){
+    std::istringstream ss(pdate);
+    ss >> std::get_time(&tm, "%Y-%m-%dT%T");
+    if(ss.fail()){
         // wrong format
         return false;
     }
diff --git a/src/string_util.h b/src/string_util.h
index 2577d49..e2eeaf6 100644
--- a/src/string_util.h
+++ b/src/string_util.h
@@ -55,12 +55,6 @@ static inline const char* SAFESTRPTR(const char *strptr) { return strptr ? strpt
 // TODO: rename to to_string?
 std::string str(const struct timespec value);
 
-#ifdef __MSYS__
-//
-// Polyfill for strptime function.
-//
-char* strptime(const char* s, const char* f, struct tm* tm);
-#endif
 //
 // Convert string to off_t.  Returns false on bad input.
 // Replacement for C++11 std::stoll.