diff --git a/include/fti/upm_stream.h b/include/fti/upm_stream.h
index 4c4d0855..fb70dd48 100644
--- a/include/fti/upm_stream.h
+++ b/include/fti/upm_stream.h
@@ -29,11 +29,11 @@
 extern "C" {
 #endif
 
-struct _upm_stream_ft {
+typedef struct _upm_stream_ft {
         /* read up to len bytes into buffer, return number of bytes read */
-        int (*upm_stream_read) (void* dev, void *buffer, int len);
+        int (*upm_stream_read) (void* dev, char *buffer, int len);
         /* write up to len bytes from buffer, return number of bytes written */
-        int (*upm_stream_write) (void* dev, void *buffer, int len);
+        int (*upm_stream_write) (void* dev, char *buffer, int len);
         /* return true if data is available to be read, false otherwise */
         bool (*upm_stream_data_available) (void* dev, unsigned int timeout);
 } upm_stream_ft;