diff --git a/i.c b/i.c
index 856a0cb..78f65b8 100644
--- a/i.c
+++ b/i.c
@@ -2727,6 +2727,19 @@ define_instruction(intp) {
   gonexti(); 
 }
 
+define_instruction(ratp) {
+  if (likely(is_fixnum(ac))) {
+    ac = bool_obj(1);
+  } else if (likely(is_flonum(ac))) {
+    double f = get_flonum(ac);
+    ac = bool_obj(f > -HUGE_VAL && f < HUGE_VAL);
+  } else {
+    ac = bool_obj(0);
+  }
+  gonexti(); 
+}
+
+
 define_instruction(nanp) {
   if (unlikely(is_fixnum(ac))) {
     ac = bool_obj(0);
diff --git a/i.h b/i.h
index 037c43e..a7dbfb2 100644
--- a/i.h
+++ b/i.h
@@ -348,6 +348,7 @@ declare_instruction(tan,        "N5",           0,  "tan",
 declare_instruction(asin,       "N6",           0,  "asin",                     '1', AUTOGL)
 declare_instruction(acos,       "N7",           0,  "acos",                     '1', AUTOGL)
 declare_instruction(atan,       "N8\0f",        0,  "atan",                     'b', AUTOGL)
+declare_instruction(ratp,       "Nv",           0,  "rational?",                '1', AUTOGL)
 declare_instruction(intp,       "Nw",           0,  "integer?",                 '1', AUTOGL)
 declare_instruction(nanp,       "Nu",           0,  "nan?",                     '1', AUTOGL)
 declare_instruction(finp,       "Nf",           0,  "finite?",                  '1', AUTOGL)
@@ -528,7 +529,6 @@ declare_instruction(igco,       "U8",           0,  "integrable-code",
 /* inlined integrables (no custom instructions) */               
 declare_integrable(NULL,        "N0",           0,  "complex?",                 '1', AUTOGL)
 declare_integrable(NULL,        "N0",           0,  "real?",                    '1', AUTOGL)
-declare_integrable(NULL,        "N0",           0,  "rational?",                '1', AUTOGL)
 declare_integrable(NULL,        "I0",           0,  "exact-integer?",           '1', AUTOGL)
 declare_integrable(NULL,        "%nI0",         0,  "exact?",                   '1', AUTOGL)
 declare_integrable(NULL,        "%nJ0",         0,  "inexact?",                 '1', AUTOGL)
diff --git a/s.c b/s.c
index df16e80..bd6ecfe 100644
--- a/s.c
+++ b/s.c
@@ -2,12 +2,6 @@
 
 char *s_code[] = {
 
-  "C", 0,
-  "@(y16:%25open-input-file)@!(y15:open-input-file)"
-  "@(y17:%25open-output-file)@!(y16:open-output-file)"
-  "@(y23:%25open-binary-input-file)@!(y22:open-binary-input-file)"
-  "@(y24:%25open-binary-output-file)@!(y23:open-binary-output-file)",
-
   "S", "let-syntax",
   "l4:y12:syntax-rules;n;l2:l2:y1:_;l2:l2:y2:kw;y4:init;;y3:...;;;l1:y5:b"
   "egin;;;l2:py1:_;pl2:l2:y2:kw;y4:init;;y3:...;;y5:forms;;;l3:py13:synta"
@@ -734,6 +728,21 @@ char *s_code[] = {
   "C", 0,
   "@(y5:port?)@!(y12:binary-port?)",
 
+  "P", "open-input-file",
+  "%1.0P40,.0?{.0]2}.1,'(s22:cannot open input file),@(y10:file-error)[22",
+
+  "P", "open-output-file",
+  "%1.0P41,.0?{.0]2}.1,'(s23:cannot open output file),@(y10:file-error)[2"
+  "2",
+
+  "P", "open-binary-input-file",
+  "%1.0P42,.0?{.0]2}.1,'(s29:cannot open binary input file),@(y10:file-er"
+  "ror)[22",
+
+  "P", "open-binary-output-file",
+  "%1.0P43,.0?{.0]2}.1,'(s30:cannot open binary output file),@(y10:file-e"
+  "rror)[22",
+
   "P", "close-port",
   "%1.0P00?{.0P60}.0P01?{.0P61]1}]1",
 
@@ -742,10 +751,10 @@ char *s_code[] = {
   "st)[12},.1,.3,&2{%0:1,:0[01},@(y16:call-with-values)[22",
 
   "P", "call-with-input-file",
-  "%2.1,.1P40,@(y14:call-with-port)[22",
+  "%2.1,${.3,@(y15:open-input-file)[01},@(y14:call-with-port)[22",
 
   "P", "call-with-output-file",
-  "%2.1,.1P41,@(y14:call-with-port)[22",
+  "%2.1,${.3,@(y16:open-output-file)[01},@(y14:call-with-port)[22",
 
   "P", "read-line",
   "%!0P51,.1u?{P10}{.1a},t,,#0.2,.4,.2,&3{%1:2R0,.0R8,.0?{.0}{'(c%0a),.2C"
diff --git a/src/s.scm b/src/s.scm
index 0c9c31f..acba02b 100644
--- a/src/s.scm
+++ b/src/s.scm
@@ -473,7 +473,7 @@
 ; (number? x)
 ; (complex? x) == number? what about inf and nan?
 ; (real? x) == number? what about inf and nan?
-; (rational? x) == number? what about inf and nan?
+; (rational? x)
 ; (integer? x)
 ; (exact? x)
 ; (inexact? x)
@@ -1376,19 +1376,19 @@
 (define textual-port? port?) ; all ports are bimodal
 (define binary-port? port?)  ; all ports are bimodal
 
-(define-inline (open-input-file fn)
+(define (open-input-file fn)
   (or (%open-input-file fn)
       (file-error "cannot open input file" fn)))
 
-(define-inline (open-output-file fn)
+(define (open-output-file fn)
   (or (%open-output-file fn)
       (file-error "cannot open output file" fn)))
 
-(define-inline (open-binary-input-file fn)
+(define (open-binary-input-file fn)
   (or (%open-binary-input-file fn)
       (file-error "cannot open binary input file" fn)))
 
-(define-inline (open-binary-output-file fn)
+(define (open-binary-output-file fn)
   (or (%open-binary-output-file fn)
       (file-error "cannot open binary output file" fn)))