diff --git a/basis/io/buffers/buffers.factor b/basis/io/buffers/buffers.factor
index 4df081b17d..49b5357d98 100644
--- a/basis/io/buffers/buffers.factor
+++ b/basis/io/buffers/buffers.factor
@@ -22,7 +22,7 @@ M: buffer dispose* ptr>> free ;
     swap >>fill 0 >>pos drop ;
 
 : buffer-capacity ( buffer -- n )
-    [ size>> ] [ fill>> ] bi - ; inline
+    [ size>> ] [ fill>> ] bi - >fixnum ; inline
 
 : buffer-empty? ( buffer -- ? )
     fill>> zero? ; inline
diff --git a/basis/io/ports/ports.factor b/basis/io/ports/ports.factor
index 569366d4b8..b2d71fd535 100644
--- a/basis/io/ports/ports.factor
+++ b/basis/io/ports/ports.factor
@@ -189,4 +189,4 @@ HINTS: decoder-read-until { string input-port utf8 } { string input-port ascii }
 
 HINTS: decoder-readln { input-port utf8 } { input-port ascii } ;
 
-HINTS: encoder-write { string output-port utf8 } { string output-port ascii } ;
+HINTS: encoder-write { object output-port utf8 } { object output-port ascii } ;