diff --git a/benchmarks.larceny/results.Larceny-r6rs b/benchmarks.larceny/results.Larceny-r6rs
index 19d1516..7b5f1b8 100644
--- a/benchmarks.larceny/results.Larceny-r6rs
+++ b/benchmarks.larceny/results.Larceny-r6rs
@@ -8130,3 +8130,63 @@ Words allocated: 6553342
 Words reclaimed: 0
 Elapsed time...: 3454 ms (User: 2052 ms; System: 1399 ms)
 Elapsed GC time: 8 ms (CPU: 9 in 25 collections.)
+
+****************************
+Benchmarking Larceny-r6rs on Fri Jul 13 13:49:43 AST 2007 under Darwin Vesuvius.local 8.9.1 Darwin Kernel Version 8.9.1: Thu Feb 22 20:55:00 PST 2007; root:xnu-792.18.15~1/RELEASE_I386 i386 i386
+
+Testing ctak under Larceny-r6rs
+Compiling...
+Larceny v0.93 "Deviated Prevert" (Nov 10 2006 04:27:45, precise:BSD Unix:unified)
+
+
+> 
+> 
+Running...
+Larceny v0.93 "Deviated Prevert" (Nov 10 2006 04:27:45, precise:BSD Unix:unified)
+
+
+> 
+Words allocated: 265286850
+Words reclaimed: 0
+Elapsed time...: 4836 ms (User: 4824 ms; System: 10 ms)
+Elapsed GC time: 369 ms (CPU: 363 in 1012 collections.)
+
+****************************
+Benchmarking Larceny-r6rs on Fri Jul 13 13:50:43 AST 2007 under Darwin Vesuvius.local 8.9.1 Darwin Kernel Version 8.9.1: Thu Feb 22 20:55:00 PST 2007; root:xnu-792.18.15~1/RELEASE_I386 i386 i386
+
+Testing fibc under Larceny-r6rs
+Compiling...
+Larceny v0.93 "Deviated Prevert" (Nov 10 2006 04:27:45, precise:BSD Unix:unified)
+
+
+> 
+> 
+Running...
+Larceny v0.93 "Deviated Prevert" (Nov 10 2006 04:27:45, precise:BSD Unix:unified)
+
+
+> 
+Words allocated: 192411298
+Words reclaimed: 0
+Elapsed time...: 4098 ms (User: 4087 ms; System: 9 ms)
+Elapsed GC time: 280 ms (CPU: 270 in 734 collections.)
+
+****************************
+Benchmarking Larceny-r6rs on Fri Jul 13 13:53:01 AST 2007 under Darwin Vesuvius.local 8.9.1 Darwin Kernel Version 8.9.1: Thu Feb 22 20:55:00 PST 2007; root:xnu-792.18.15~1/RELEASE_I386 i386 i386
+
+Testing mbrot under Larceny-r6rs
+Compiling...
+Larceny v0.93 "Deviated Prevert" (Nov 10 2006 04:27:45, precise:BSD Unix:unified)
+
+
+> 
+> 
+Running...
+Larceny v0.93 "Deviated Prevert" (Nov 10 2006 04:27:45, precise:BSD Unix:unified)
+
+
+> 
+Words allocated: 551809361
+Words reclaimed: 0
+Elapsed time...: 2246 ms (User: 2230 ms; System: 15 ms)
+Elapsed GC time: 753 ms (CPU: 762 in 2105 collections.)
diff --git a/benchmarks/BUGS b/benchmarks/BUGS
index dd2e259..5394358 100644
--- a/benchmarks/BUGS
+++ b/benchmarks/BUGS
@@ -4,8 +4,6 @@
 * slatex needs char-alphabetic?
 * compiler needs string-downcase
 
-* ctak crashes with a bus error.
-* fibc crashes with a segfault.
 * ntakl kinda slow
 * string too slow
 * nbody does not work
diff --git a/src/ikarus.boot b/src/ikarus.boot
index e23222f..f9cfd09 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/libaltcogen.ss b/src/libaltcogen.ss
index 8ec648e..eba99b5 100644
--- a/src/libaltcogen.ss
+++ b/src/libaltcogen.ss
@@ -192,6 +192,47 @@
 
 (include "pass-specify-rep.ss")
 
+
+(define (insert-stack-overflow-check x)
+  (define who 'insert-stack-overflow-check)
+  
+  (define (Tail x) #t)
+
+  (define (insert-check x)
+    (make-seq 
+      (make-shortcut 
+        (make-conditional 
+          (make-primcall '< 
+            (list esp (make-primcall 'mref (list pcr (make-constant 16)))))
+          (make-primcall 'interrupt '())
+          (make-primcall 'nop '()))
+        (make-forcall "ik_stack_overflow" '()))
+      x))
+
+  (define (ClambdaCase x) 
+    (record-case x
+      [(clambda-case info body)
+       (make-clambda-case info (Main body))]))
+  ;;;
+  (define (Clambda x)
+    (record-case x
+      [(clambda label case* free*)
+       (make-clambda label (map ClambdaCase case*) free*)]))
+  ;;;
+  (define (Main x)
+    (if (Tail x) 
+        (insert-check x) 
+        x))
+  ;;;
+  (define (Program x)
+    (record-case x 
+      [(codes code* body)
+       (make-codes (map Clambda code*) (Main body))]))
+  ;;;
+  (Program x))
+
+
+
 (define parameter-registers '(%edi)) 
 (define return-value-register '%eax)
 (define cp-register '%edi)
@@ -2737,6 +2778,7 @@
   (let* ([x (introduce-primcalls x)]
          [x (eliminate-fix x)]
          [x (specify-representation x)]
+         [x (insert-stack-overflow-check x)]
          [x (impose-calling-convention/evaluation-order x)]
          [x (time-it "frame" (lambda () (assign-frame-sizes x)))]
          [x (time-it "register" (lambda () (color-by-chaitin x)))]