https://github.com/ImageMagick/ImageMagick/issues/945

diff --git a/MagickCore/blob.c b/MagickCore/blob.c
index 3fafc5998a460b6a172c1b3b4b7fdd0e72417c32..226f03e91b7bc071c8f4eae48a148f5b81577c8a 100644 (file)
--- a/MagickCore/blob.c
+++ b/MagickCore/blob.c
@@ -2719,7 +2719,7 @@ MagickExport MagickBooleanType IsBlobSeekable(const Image *image)
       int
         status;
 
-      if (fileno(blob_info->file_info.file) == -1)
+      if (blob_info->file_info.file == (FILE *) NULL)
         return(MagickFalse);
       status=fseek(blob_info->file_info.file,0,SEEK_CUR);
       return(status == -1 ? MagickFalse : MagickTrue);