diff -ur gdcm-3.0.17.orig/Utilities/gdcmext/mec_mr3_io.c gdcm-3.0.17/Utilities/gdcmext/mec_mr3_io.c
--- gdcm-3.0.17.orig/Utilities/gdcmext/mec_mr3_io.c	2022-09-05 10:44:18.058943134 -0400
+++ gdcm-3.0.17/Utilities/gdcmext/mec_mr3_io.c	2022-09-05 11:28:44.339613356 -0400
@@ -23,7 +23,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#ifndef _MSC_VER
+#if !defined(_MSC_VER) && !defined(__MINGW32__) 
 #include <iconv.h>
 #endif
 #if defined(_MSC_VER) && (_MSC_VER < 1900)
@@ -54,7 +54,7 @@
 
 struct app {
   struct stream *in;
-#ifndef _MSC_VER
+#if !defined(_MSC_VER) && !defined(__MINGW32__) 
   iconv_t conv;
 #endif
   void *shift_jis_buffer;
@@ -62,7 +62,7 @@
 
 static struct app *create_app(struct app *self, struct stream *in) {
   self->in = in;
-#ifndef _MSC_VER
+#if !defined(_MSC_VER) && !defined(__MINGW32__) 
   self->conv = iconv_open("utf-8", "shift-jis");
   assert(self->conv != (iconv_t)-1);
 #endif
@@ -132,7 +132,7 @@
 }
 
 static void *aligned_alloc_impl(size_t alignment, size_t size) {
-#ifdef _MSC_VER
+#if defined(_MSC_VER) || defined(__MINGW32__) 
   return _aligned_malloc(size, alignment);
 #else
   return aligned_alloc(alignment, size);
@@ -352,7 +352,7 @@
   const size_t guesstimate = len < 128 ? 128 : len * 2;
   self->shift_jis_buffer = realloc(self->shift_jis_buffer, guesstimate);
   char *dest_str = self->shift_jis_buffer;
-#ifndef _MSC_VER
+#if !defined(_MSC_VER) && !defined(__MINGW32__) 
   char *in_str = str;
   char *out_str = dest_str;
   size_t inbytes = len;
@@ -831,12 +831,12 @@
     good = good && read_group(self, group, nitems, &info, &data);
   }
   // release memory:
-#ifdef _MSC_VER
+#if defined(_MSC_VER) || defined(__MINGW32__) 
   _aligned_free(data.buffer);
 #else
   free(data.buffer);
 #endif
-#ifndef _MSC_VER
+#if !defined(_MSC_VER) && !defined(__MINGW32__) 
   iconv_close(self->conv);
 #endif
   free(self->shift_jis_buffer);
Only in gdcm-3.0.17.orig/Utilities/gdcmext: .mec_mr3_io.c.swp