diff --git a/libImaging/Imaging.h b/libImaging/Imaging.h
index 4a2c650ed..c341ac84e 100644
--- a/libImaging/Imaging.h
+++ b/libImaging/Imaging.h
@@ -528,9 +528,9 @@ enum {
 extern ImagingIncrementalCodec ImagingIncrementalCodecCreate(ImagingIncrementalCodecEntry codec_entry, Imaging im, ImagingCodecState state, int read_or_write, int seekable, int fd);
 extern void ImagingIncrementalCodecDestroy(ImagingIncrementalCodec codec);
 extern int ImagingIncrementalCodecPushBuffer(ImagingIncrementalCodec codec, UINT8 *buf, int bytes);
-extern ssize_t ImagingIncrementalCodecRead(ImagingIncrementalCodec codec, void *buffer, size_t bytes);
+extern Py_ssize_t ImagingIncrementalCodecRead(ImagingIncrementalCodec codec, void *buffer, size_t bytes);
 extern off_t ImagingIncrementalCodecSkip(ImagingIncrementalCodec codec, off_t bytes);
-extern ssize_t ImagingIncrementalCodecWrite(ImagingIncrementalCodec codec, const void *buffer, size_t bytes);
+extern Py_ssize_t ImagingIncrementalCodecWrite(ImagingIncrementalCodec codec, const void *buffer, size_t bytes);
 extern off_t ImagingIncrementalCodecSeek(ImagingIncrementalCodec codec, off_t bytes);
 extern size_t ImagingIncrementalCodecBytesInBuffer(ImagingIncrementalCodec codec);