fix loc.Location, re-enable tip
diff --git a/.travis.yml b/.travis.yml
index 7b3349f..13f087a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@
   - 1.4.3
   - 1.5.4
   - 1.6.1
+  - tip
 
 script:
   - go test -v ./...
diff --git a/errors.go b/errors.go
index cbe07f5..7ebcbba 100644
--- a/errors.go
+++ b/errors.go
@@ -59,7 +59,7 @@
 type loc uintptr
 
 func (l loc) Location() (string, int) {
-	pc := uintptr(l)
+	pc := uintptr(l) - 1
 	fn := runtime.FuncForPC(pc)
 	if fn == nil {
 		return "unknown", 0