diff --git a/internal/debug/debug.go b/internal/debug/debug.go
index 2936c17..905a2b3 100644
--- a/internal/debug/debug.go
+++ b/internal/debug/debug.go
@@ -56,6 +56,11 @@ var (
 	}
 )
 
+// Err2PackageID is the name ID of err2. When its API will update, e.g., v2, the
+// ID must be updated as following "lainio/err2/v2", etc. See tests for
+// isFuncAnchor.
+const Err2PackageID = "lainio/err2"
+
 func (si StackInfo) fullName() string {
 	dot := ""
 	if si.PackageName != "" && si.FuncName != "" {
diff --git a/internal/debug/debug_test.go b/internal/debug/debug_test.go
index 8923f56..552a327 100644
--- a/internal/debug/debug_test.go
+++ b/internal/debug/debug_test.go
@@ -119,28 +119,65 @@ func TestIsFuncAnchor(t *testing.T) {
 			StackInfo{"", "", 0, PackageRegexp, nil, false}}, true},
 		{"short", args{
 			"github.com/lainio/err2.printStackIf({0x1545d2, 0x6}, 0x0, {0x12e3e0?, 0x188f50?})",
-			StackInfo{"", "", 0, nil, nil, false}}, true},
+			StackInfo{Err2PackageID, "", 0, nil, nil, false}}, true},
 		{"short-but-false", args{
 			"github.com/lainio/err2.printStackIf({0x1545d2, 0x6}, 0x0, {0x12e3e0?, 0x188f50?})",
-			StackInfo{"err2", "Handle", 0, nil, nil, false}}, false},
+			StackInfo{Err2PackageID, "Handle", 0, nil, nil, false}}, false},
 		{"medium", args{
 			"github.com/lainio/err2.Returnw(0x40000b3e60, {0x0, 0x0}, {0x0, 0x0, 0x0})",
-			StackInfo{"err2", "Returnw", 0, nil, nil, false}}, true},
+			StackInfo{Err2PackageID, "Returnw", 0, nil, nil, false}}, true},
 		{"medium-but-false", args{
 			"github.com/lainio/err2.Returnw(0x40000b3e60, {0x0, 0x0}, {0x0, 0x0, 0x0})",
-			StackInfo{"err2", "Return(", 0, nil, nil, false}}, false},
+			StackInfo{Err2PackageID, "Return(", 0, nil, nil, false}}, false},
 		{"long", args{
 			"github.com/lainio/err2.Handle(0x40000b3ed8, 0x40000b3ef8)",
-			StackInfo{"err2", "Handle", 0, nil, nil, false}}, true},
+			StackInfo{Err2PackageID, "Handle", 0, nil, nil, false}}, true},
 		{"package name only", args{
 			"github.com/lainio/err2/try.To1[...](...)",
-			StackInfo{"lainio/err2", "", 0, nil, nil, false}}, true},
+			StackInfo{Err2PackageID, "", 0, nil, nil, false}}, true},
+
+		// From bug (issue #30 and PR #31) tests, Handle name in own pkg
+		{"user pkg containing Handle should not match", args{
+			"mainHandle.First(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{Err2PackageID, "Handle", 0, nil, nil, false}}, false},
+		{"user function containing Handle should not match", args{
+			"main.FirstHandle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{Err2PackageID, "Handle", 0, nil, nil, false}}, false},
+		{"user function containing Handle matches err2.Handle", args{
+			"github.com/lainio/err2.Handle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{Err2PackageID, "Handle", 0, nil, nil, false}}, true},
+		{"user function named exactly Handle should not match", args{
+			"main.Handle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{Err2PackageID, "Handle", 0, nil, nil, false}}, false},
+		{"user package function named Handle should not match", args{
+			"mypackage.Handle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{"err2", "Handle", 0, nil, nil, false}}, false},
+		{"err2.Handle should match", args{
+			"err2.Handle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{"err2", "Handle", 0, nil, nil, false}}, true},
+		{"lainio/err2.Handle should match", args{
+			"github.com/lainio/err2.Handle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{Err2PackageID, "Handle", 0, nil, nil, false}}, true},
+		{"user package with err2 in path should not match", args{
+			"github.com/mycompany/err2/mypackage.Handle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{Err2PackageID, "Handle", 0, nil, nil, false}}, false},
+		{"non-err2 versioned package should not match", args{
+			"github.com/someone/otherpkg/v2.Handle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{Err2PackageID, "Handle", 0, nil, nil, false}}, false},
+
+		// See the PackageID!!
+		{"versioned err2/v2.Handle should match", args{
+			"github.com/lainio/err2/v2.Handle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{Err2PackageID + "/v2", "Handle", 0, nil, nil, false}}, true},
+		{"versioned err2/v10.Handle should match", args{
+			"github.com/lainio/err2/v10.Handle(0x40000b3ed8, 0x40000b3ef8)",
+			StackInfo{Err2PackageID + "/v10", "Handle", 0, nil, nil, false}}, true},
 	}
 	for _, ttv := range tests {
 		tt := ttv
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
-			expect.Equal(t, tt.retval, tt.isFuncAnchor(tt.input))
+			expect.Equal(t, tt.isFuncAnchor(tt.input), tt.retval)
 		})
 	}
 }
diff --git a/internal/handler/handler.go b/internal/handler/handler.go
index 98e3831..207e4d9 100644
--- a/internal/handler/handler.go
+++ b/internal/handler/handler.go
@@ -349,7 +349,7 @@ func doBuildFormatStr(info *Info, lvl int) (fs string, ok bool) {
 		fnName = info.CallerName
 	}
 	funcName, _, _, ok := debug.FuncName(debug.StackInfo{
-		PackageName: "",
+		PackageName: debug.Err2PackageID, // limit fn name search to err2 pkg
 		FuncName:    fnName,
 		Level:       lvl,
 	})
diff --git a/internal/handler/handler_test.go b/internal/handler/handler_test.go
index 1755a0d..0aae249 100644
--- a/internal/handler/handler_test.go
+++ b/internal/handler/handler_test.go
@@ -157,7 +157,7 @@ func TestPreProcess_debug(t *testing.T) {
 	expect.ThatNot(t, nilHandlerCalled)
 
 	// See the name of this test function. Decamel it + error
-	const want = "testing: t runner: error"
+	const want = "error"
 	expect.Equal(t, myErrVal.Error(), want)
 
 	resetCalled()
diff --git a/samples/main-db-sample.go b/samples/db-sample.go
similarity index 100%
rename from samples/main-db-sample.go
rename to samples/db-sample.go
diff --git a/samples/main.go b/samples/main.go
index 9d901e9..f7d8806 100644
--- a/samples/main.go
+++ b/samples/main.go
@@ -16,6 +16,7 @@ var (
 		"play",
 		"runs the wanted playground: db, play, nil, assert,"+
 			"\nassert-keep (= uses assert.Debug in GLS),"+
+			"\noverlap (= our fn names can be like MyHandle, myCatch, ..),"+
 			"\nplay-recursion (= runs recursion example)",
 	)
 	isErr = flag.Bool("err", false, "tells if we want to have an error")
@@ -41,6 +42,8 @@ func main() {
 	}
 
 	switch *mode {
+	case "overlap":
+		doOverlapMain()
 	case "db":
 		doDBMain()
 	case "nil":
diff --git a/samples/main-nil.go b/samples/nil.go
similarity index 100%
rename from samples/main-nil.go
rename to samples/nil.go
diff --git a/samples/overlap.go b/samples/overlap.go
new file mode 100644
index 0000000..f276fb6
--- /dev/null
+++ b/samples/overlap.go
@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/lainio/err2"
+	"github.com/lainio/err2/try"
+)
+
+func doOverlapMain() {
+	err := FirstHandle()
+	fmt.Printf("Final error: %v\n", err)
+}
+
+func FirstHandle() (err error) {
+	defer err2.Handle(&err)
+	try.To(SecondHandle())
+	return nil
+}
+
+func SecondHandle() (err error) {
+	defer err2.Handle(&err)
+	try.T(fmt.Errorf("my error"))("my call lvl annotation")
+	return nil
+}
diff --git a/samples/main-play.go b/samples/play.go
similarity index 100%
rename from samples/main-play.go
rename to samples/play.go