diff --git a/src/ikarus.boot b/src/ikarus.boot
index f9465b3..5388539 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/ikarus.core.ss b/src/ikarus.core.ss
index bb12773..54a3c64 100644
--- a/src/ikarus.core.ss
+++ b/src/ikarus.core.ss
@@ -16,11 +16,6 @@
   (lambda (x)
     (pointer-value x)))
 
-(primitive-set! 'date-string
-  (lambda ()
-    (let ([s (make-string 10)])
-      (foreign-call "ikrt_strftime" s "%F")
-      s)))
 
 
 )
diff --git a/src/ikarus.date-string.ss b/src/ikarus.date-string.ss
new file mode 100644
index 0000000..f0cdd64
--- /dev/null
+++ b/src/ikarus.date-string.ss
@@ -0,0 +1,9 @@
+
+(library (ikarus date-string)
+  (export date-string)
+  (import (except (ikarus) date-string))
+  (define date-string
+    (lambda ()
+      (let ([s (make-string 10)])
+        (foreign-call "ikrt_strftime" s "%F")
+        s))))
diff --git a/src/makefile.ss b/src/makefile.ss
index f13e042..2d41205 100755
--- a/src/makefile.ss
+++ b/src/makefile.ss
@@ -35,6 +35,7 @@
       "ikarus.chars.ss"
       "ikarus.records.ss"
       "ikarus.strings.ss"
+      "ikarus.date-string.ss"
       "ikarus.symbols.ss"
       "ikarus.vectors.ss"
       "ikarus.numerics.ss"