diff --git a/extract/ExtBasic.c b/extract/ExtBasic.c
index 17808f91..97ecffd7 100644
--- a/extract/ExtBasic.c
+++ b/extract/ExtBasic.c
@@ -1267,6 +1267,8 @@ extComputeEffectiveLW(rlengthptr, rwidthptr, numregions, chop)
 	    case BD_RIGHT:  oppdir = BD_LEFT;   break;
 	    case BD_TOP:    oppdir = BD_BOTTOM; break;
 	    case BD_BOTTOM: oppdir = BD_TOP;    break;
+	    default:        ASSERT(FALSE, "oppdir"); /* should never happen */
+	                    oppdir = 0;         break;
 	}
 
 	/* First pass: Find the distance of the closest segment within	*/