diff --git a/libs/spandsp/src/fax_modems.c b/libs/spandsp/src/fax_modems.c
index b919f75654..c271b34f8c 100644
--- a/libs/spandsp/src/fax_modems.c
+++ b/libs/spandsp/src/fax_modems.c
@@ -87,7 +87,7 @@
 
 #define HDLC_FRAMING_OK_THRESHOLD               5
 
-int fax_modems_v17_v21_rx(void *user_data, const int16_t amp[], int len)
+SPAN_DECLARE(int) fax_modems_v17_v21_rx(void *user_data, const int16_t amp[], int len)
 {
     fax_modems_state_t *s;
 
@@ -106,7 +106,7 @@ int fax_modems_v17_v21_rx(void *user_data, const int16_t amp[], int len)
 }
 /*- End of function --------------------------------------------------------*/
 
-int fax_modems_v27ter_v21_rx(void *user_data, const int16_t amp[], int len)
+SPAN_DECLARE(int) fax_modems_v27ter_v21_rx(void *user_data, const int16_t amp[], int len)
 {
     fax_modems_state_t *s;
 
@@ -125,7 +125,7 @@ int fax_modems_v27ter_v21_rx(void *user_data, const int16_t amp[], int len)
 }
 /*- End of function --------------------------------------------------------*/
 
-int fax_modems_v29_v21_rx(void *user_data, const int16_t amp[], int len)
+SPAN_DECLARE(int) fax_modems_v29_v21_rx(void *user_data, const int16_t amp[], int len)
 {
     fax_modems_state_t *s;
 
diff --git a/libs/spandsp/src/t4.c b/libs/spandsp/src/t4.c
index 381be75b68..549d2c74a2 100644
--- a/libs/spandsp/src/t4.c
+++ b/libs/spandsp/src/t4.c
@@ -410,7 +410,7 @@ static int test_tiff_directory_info(t4_state_t *s)
         return -1;
     parm = 0;
     TIFFGetField(t->tiff_file, TIFFTAG_IMAGEWIDTH, &parm);
-    if (s->image_width != parm)
+    if (s->image_width != (int)parm)
     {
 printf("Width changed\n");
         return 1;
@@ -1959,7 +1959,7 @@ SPAN_DECLARE(t4_state_t *) t4_tx_init(t4_state_t *s, const char *file, int start
     s->stop_page = (stop_page >= 0)  ?  stop_page : INT_MAX;
 
     if (!TIFFSetDirectory(s->tiff.tiff_file, (tdir_t) s->current_page))
-        return -1;
+        return NULL;
     if (get_tiff_directory_info(s))
     {
         close_tiff_input_file(s);