diff --git a/contrib/clipper/clipper.cpp b/contrib/clipper/clipper.cpp
index b2316ccd5..c8c62bc2a 100644
--- a/contrib/clipper/clipper.cpp
+++ b/contrib/clipper/clipper.cpp
@@ -26,7 +26,7 @@
 * Paper no. DETC2005-85513 pp. 565-575                                         *
 * ASME 2005 International Design Engineering Technical Conferences             *
 * and Computers and Information in Engineering Conference (IDETC/CIE2005)      *
-* September 24–28, 2005 , Long Beach, California, USA                          *
+* September 24–28, 2005 , Long Beach, California, USA                          *
 * http://www.me.berkeley.edu/~mcmains/pubs/DAC05OffsetPolygon.pdf              *
 *                                                                              *
 *******************************************************************************/
diff --git a/contrib/clipper/clipper.hpp b/contrib/clipper/clipper.hpp
index f6f196d0d..3d6510dff 100644
--- a/contrib/clipper/clipper.hpp
+++ b/contrib/clipper/clipper.hpp
@@ -26,7 +26,7 @@
 * Paper no. DETC2005-85513 pp. 565-575                                         *
 * ASME 2005 International Design Engineering Technical Conferences             *
 * and Computers and Information in Engineering Conference (IDETC/CIE2005)      *
-* September 24–28, 2005 , Long Beach, California, USA                          *
+* September 24–28, 2005 , Long Beach, California, USA                          *
 * http://www.me.berkeley.edu/~mcmains/pubs/DAC05OffsetPolygon.pdf              *
 *                                                                              *
 *******************************************************************************/