diff --git a/tests/comparePGXimages.c b/tests/comparePGXimages.c
index 77714ddc..3db1dca8 100644
--- a/tests/comparePGXimages.c
+++ b/tests/comparePGXimages.c
@@ -145,6 +145,12 @@ static opj_image_t* readImageFromFileTIF(const char* filename, int nbFilenamePGX
   opj_image_cmptparm_t* param_image_read;
   int** data;
 
+  /* conformance test suite produce annoying warning:
+   * TIFFReadDirectory: Warning, /.../data/baseline/conformance/jp2_1.tif: unknown field with tag 37724 (0x935c) encountered.
+   * On Win32 this open a message box by default, so remove it from the test suite:
+   */
+  TIFFSetWarningHandler(NULL);
+
   /* If separator is empty => nb file to read is equal to one*/
   if ( strlen(separator) == 0 )
     nbFilenamePGX = 1;