diff --git a/cmd/gotext/examples/extract/catalog.go b/cmd/gotext/examples/extract/catalog.go
index bc6130a..65570f8 100644
--- a/cmd/gotext/examples/extract/catalog.go
+++ b/cmd/gotext/examples/extract/catalog.go
@@ -14,7 +14,10 @@
 }
 
 func (d *dictionary) Lookup(key string) (data string, ok bool) {
-	p := messageKeyToIndex[key]
+	p, ok := messageKeyToIndex[key]
+	if !ok {
+		return "", false
+	}
 	start, end := d.index[p], d.index[p+1]
 	if start == end {
 		return "", false
diff --git a/cmd/gotext/examples/extract_http/catalog_gen.go b/cmd/gotext/examples/extract_http/catalog_gen.go
index 2c410dc..4327d34 100644
--- a/cmd/gotext/examples/extract_http/catalog_gen.go
+++ b/cmd/gotext/examples/extract_http/catalog_gen.go
@@ -14,7 +14,10 @@
 }
 
 func (d *dictionary) Lookup(key string) (data string, ok bool) {
-	p := messageKeyToIndex[key]
+	p, ok := messageKeyToIndex[key]
+	if !ok {
+		return "", false
+	}
 	start, end := d.index[p], d.index[p+1]
 	if start == end {
 		return "", false
diff --git a/message/pipeline/generate.go b/message/pipeline/generate.go
index 2770d14..bb1f85b 100644
--- a/message/pipeline/generate.go
+++ b/message/pipeline/generate.go
@@ -297,7 +297,10 @@
 }
 
 func (d *dictionary) Lookup(key string) (data string, ok bool) {
-	p := messageKeyToIndex[key]
+	p, ok := messageKeyToIndex[key]
+	if !ok {
+		return "", false
+	}
 	start, end := d.index[p], d.index[p+1]
 	if start == end {
 		return "", false
diff --git a/message/pipeline/testdata/ssa/catalog_gen.go b/message/pipeline/testdata/ssa/catalog_gen.go
index 539d741..dce54af 100644
--- a/message/pipeline/testdata/ssa/catalog_gen.go
+++ b/message/pipeline/testdata/ssa/catalog_gen.go
@@ -14,7 +14,10 @@
 }
 
 func (d *dictionary) Lookup(key string) (data string, ok bool) {
-	p := messageKeyToIndex[key]
+	p, ok := messageKeyToIndex[key]
+	if !ok {
+		return "", false
+	}
 	start, end := d.index[p], d.index[p+1]
 	if start == end {
 		return "", false
diff --git a/message/pipeline/testdata/test1/catalog_gen.go.want b/message/pipeline/testdata/test1/catalog_gen.go.want
index 7d93f48..890ef51 100644
--- a/message/pipeline/testdata/test1/catalog_gen.go.want
+++ b/message/pipeline/testdata/test1/catalog_gen.go.want
@@ -14,7 +14,10 @@
 }
 
 func (d *dictionary) Lookup(key string) (data string, ok bool) {
-	p := messageKeyToIndex[key]
+	p, ok := messageKeyToIndex[key]
+	if !ok {
+		return "", false
+	}
 	start, end := d.index[p], d.index[p+1]
 	if start == end {
 		return "", false
diff --git a/message/pipeline/testdata/test1/catalog_test.go b/message/pipeline/testdata/test1/catalog_test.go
index eeb7c25..34f8b86 100644
--- a/message/pipeline/testdata/test1/catalog_test.go
+++ b/message/pipeline/testdata/test1/catalog_test.go
@@ -23,6 +23,10 @@
 		key:  "Hello world!\n",
 		want: "Hello world!\n",
 	}, {
+		lang: "en",
+		key:  "non-existing-key\n",
+		want: "non-existing-key\n",
+	}, {
 		lang: "de",
 		key:  "Hello world!\n",
 		want: "Hallo Welt!\n",