diff --git a/examples/stringsvc2/instrumenting.go b/examples/stringsvc2/instrumenting.go
index b6b607c..675617d 100644
--- a/examples/stringsvc2/instrumenting.go
+++ b/examples/stringsvc2/instrumenting.go
@@ -16,7 +16,7 @@
 
 func (mw instrumentingMiddleware) Uppercase(s string) (output string, err error) {
 	defer func(begin time.Time) {
-		lvs := []string{"method", "uppercase", "error", fmt.Sprint(err == nil)}
+		lvs := []string{"method", "uppercase", "error", fmt.Sprint(err != nil)}
 		mw.requestCount.With(lvs...).Add(1)
 		mw.requestLatency.With(lvs...).Observe(time.Since(begin).Seconds())
 	}(time.Now())
@@ -27,7 +27,7 @@
 
 func (mw instrumentingMiddleware) Count(s string) (n int) {
 	defer func(begin time.Time) {
-		lvs := []string{"method", "count"}
+		lvs := []string{"method", "count", "error", "false"}
 		mw.requestCount.With(lvs...).Add(1)
 		mw.requestLatency.With(lvs...).Observe(time.Since(begin).Seconds())
 		mw.countResult.Observe(float64(n))
diff --git a/examples/stringsvc3/instrumenting.go b/examples/stringsvc3/instrumenting.go
index 8fa0575..b21c016 100644
--- a/examples/stringsvc3/instrumenting.go
+++ b/examples/stringsvc3/instrumenting.go
@@ -26,7 +26,7 @@
 
 func (mw instrmw) Uppercase(s string) (output string, err error) {
 	defer func(begin time.Time) {
-		lvs := []string{"method", "uppercase", "error", fmt.Sprint(err == nil)}
+		lvs := []string{"method", "uppercase", "error", fmt.Sprint(err != nil)}
 		mw.requestCount.With(lvs...).Add(1)
 		mw.requestLatency.With(lvs...).Observe(time.Since(begin).Seconds())
 	}(time.Now())
@@ -37,7 +37,7 @@
 
 func (mw instrmw) Count(s string) (n int) {
 	defer func(begin time.Time) {
-		lvs := []string{"method", "count"}
+		lvs := []string{"method", "count", "error", "false"}
 		mw.requestCount.With(lvs...).Add(1)
 		mw.requestLatency.With(lvs...).Observe(time.Since(begin).Seconds())
 		mw.countResult.Observe(float64(n))