diff --git a/retropikzel/r7rs-pffi/version/guile.scm b/retropikzel/r7rs-pffi/version/guile.scm
index 9cdb1a4..02f3916 100644
--- a/retropikzel/r7rs-pffi/version/guile.scm
+++ b/retropikzel/r7rs-pffi/version/guile.scm
@@ -34,7 +34,7 @@
               ((equal? type 'int64) int64)
               ((equal? type 'uint64) uint64)
               ((equal? type 'char) int8)
-              ((equal? type 'unsigned-char) int8)
+              ((equal? type 'unsigned-char) uint8)
               ((equal? type 'short) short)
               ((equal? type 'unsigned-short) unsigned-short)
               ((equal? type 'int) int)
diff --git a/retropikzel/r7rs-pffi/version/racket.scm b/retropikzel/r7rs-pffi/version/racket.scm
index c55633d..ad6744b 100644
--- a/retropikzel/r7rs-pffi/version/racket.scm
+++ b/retropikzel/r7rs-pffi/version/racket.scm
@@ -35,7 +35,7 @@
          ((equal? type 'int64) _int64)
          ((equal? type 'uint64) _uint64)
          ((equal? type 'char) _int8)
-         ((equal? type 'unsigned-char) _int8)
+         ((equal? type 'unsigned-char) _uint8)
          ((equal? type 'short) _short)
          ((equal? type 'unsigned-short) _ushort)
          ((equal? type 'int) _int)