diff --git a/urjtag/ChangeLog b/urjtag/ChangeLog
index cb62e87a..5f903378 100644
--- a/urjtag/ChangeLog
+++ b/urjtag/ChangeLog
@@ -17,6 +17,10 @@
   * src/svf/svf_bison.y: Avoid calling strlen() multiple times on the same
     string.  Fix by Frans Meulenbroeks.
 
+  * src/svf/svf_bison.y: Use known string length to call strcpy() rather than
+    strcat().  This avoids having to rescan for the end of the string.  Fix by
+    Frans Meulenbroeks.
+
 2010-08-26  Mike Frysinger  <vapier@gentoo.org>
 
   * src/tap/cable/gpio.c: Rewrite to use raw file descriptors when working with
diff --git a/urjtag/src/svf/svf_bison.y b/urjtag/src/svf/svf_bison.y
index 979c5836..92aacc21 100644
--- a/urjtag/src/svf/svf_bison.y
+++ b/urjtag/src/svf/svf_bison.y
@@ -312,7 +312,7 @@ hexa_num_sequence
                      $1.buflen = newlen;
                  }
                  if ($1.buf != NULL) {
-                     strcat ($1.buf, $2);
+                     strcpy ($1.buf + $1.strlen, $2);
                      $1.strlen += frag_len;
                  }
                  free ($2);