diff --git a/benchmarks/r6rs-benchmarks/slatex.ss b/benchmarks/r6rs-benchmarks/slatex.ss
index be286c3..9bcf099 100644
--- a/benchmarks/r6rs-benchmarks/slatex.ss
+++ b/benchmarks/r6rs-benchmarks/slatex.ss
@@ -6,7 +6,11 @@
   
 (library (r6rs-benchmarks slatex)
   (export main)
-  (import (r6rs) (r6rs mutable-pairs) (r6rs-benchmarks))
+  (import 
+    (r6rs) 
+    (r6rs unicode)
+    (r6rs mutable-pairs)
+    (r6rs-benchmarks))
 
   (define *op-sys* 'unix)
   
diff --git a/src/ikarus.boot b/src/ikarus.boot
index 1283ea4..4b741ef 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/makefile.ss b/src/makefile.ss
index 66fbc06..d656428 100755
--- a/src/makefile.ss
+++ b/src/makefile.ss
@@ -120,6 +120,7 @@
     [rfl         (r6rs arithmetic flonums)    #t]
     [mutable-pairs (r6rs mutable-pairs)       #t]
     [unicode     (r6rs unicode)               #t]
+    [ios         (r6rs i/o simple)             #t]
     [cm          (chez modules)               #t]
     [$all        (ikarus system $all)         #f]
     [$pairs      (ikarus system $pairs)       #f]
@@ -154,6 +155,7 @@
     [mutable-pairs (r6rs mutable-pairs)       #t]
     [unicode     (r6rs unicode)               #t]
     [rfl         (r6rs arithmetic flonums)    #t]
+    [ios         (r6rs i/o simple)             #t]
     [cm          (chez modules)               #t]
     [$all        (ikarus system $all)         #f]
     [$pairs      (ikarus system $pairs)       #f]
@@ -317,7 +319,7 @@
     [string-set!             i r]
     [string-length           i r]
     [string=?                i r]
-    [string-ci=?                i r]
+    [string-ci=?             i unicode]
     [substring               i r]
     [string-append           i r]
     [string->list            i r]
@@ -510,7 +512,7 @@
     [read                    i r]
     [read-char               i r]
     [read-token              i]
-    [peek-char               i]
+    [peek-char               i ios]
     [unread-char             i]
     [newline                 i r]
     [printf                  i]