diff --git a/src/Lib/terragear/tg_contour.cxx b/src/Lib/terragear/tg_contour.cxx
index d422edde..46a999b8 100644
--- a/src/Lib/terragear/tg_contour.cxx
+++ b/src/Lib/terragear/tg_contour.cxx
@@ -38,7 +38,7 @@ double tgContour::GetMinimumAngle( void ) const
 
         p2_index = i;
 
-        if ( i == size ) {
+        if ( i == size - 1 ) {
             p3_index = 0;
         } else {
             p3_index = i + 1;
@@ -852,4 +852,4 @@ std::ostream& operator<< ( std::ostream& output, const tgContour& subject )
     output << "Hole: " << subject.hole << "\n";
 
     return output;
-}
\ No newline at end of file
+}