diff --git a/src/curl.cpp b/src/curl.cpp
index cdca1a4..f3d3029 100644
--- a/src/curl.cpp
+++ b/src/curl.cpp
@@ -37,6 +37,11 @@
 #include "string_util.h"
 #include "addhead.h"
 
+// Use the polyfill in MSYS2 environment
+#ifdef __MSYS__
+#include "strcasestr.h"
+#endif
+
 //-------------------------------------------------------------------
 // Symbols
 //-------------------------------------------------------------------
diff --git a/src/metaheader.cpp b/src/metaheader.cpp
index 19b236c..bdf533a 100644
--- a/src/metaheader.cpp
+++ b/src/metaheader.cpp
@@ -28,6 +28,11 @@
 #include "metaheader.h"
 #include "string_util.h"
 
+// Use the polyfill in MSYS2 environment
+#ifdef __MSYS__
+#include "strptime.h"
+#endif
+
 //-------------------------------------------------------------------
 // Utility functions for convert
 //-------------------------------------------------------------------
diff --git a/src/string_util.cpp b/src/string_util.cpp
index 1a981e1..9bb674b 100644
--- a/src/string_util.cpp
+++ b/src/string_util.cpp
@@ -32,6 +32,11 @@
 #include "s3fs.h"
 #include "string_util.h"
 
+// Use the polyfill in MSYS2 environment
+#ifdef __MSYS__
+#include "strptime.h"
+#endif
+
 //-------------------------------------------------------------------
 // Global variables
 //-------------------------------------------------------------------