diff --git a/internal/pkg/lib/tsv_codec.go b/internal/pkg/lib/tsv_codec.go
index 2320320d0..fabce47c9 100644
--- a/internal/pkg/lib/tsv_codec.go
+++ b/internal/pkg/lib/tsv_codec.go
@@ -46,22 +46,21 @@ func TSVDecodeField(input string) string {
 // TSVEncodeField is for the TSV record-writer.
 func TSVEncodeField(input string) string {
 	var buffer bytes.Buffer
-	for i := range input {
-		c := input[i]
-		if c == '\\' {
+	for _, r := range input {
+		if r == '\\' {
 			buffer.WriteByte('\\')
 			buffer.WriteByte('\\')
-		} else if c == '\n' {
+		} else if r == '\n' {
 			buffer.WriteByte('\\')
 			buffer.WriteByte('n')
-		} else if c == '\r' {
+		} else if r == '\r' {
 			buffer.WriteByte('\\')
 			buffer.WriteByte('r')
-		} else if c == '\t' {
+		} else if r == '\t' {
 			buffer.WriteByte('\\')
 			buffer.WriteByte('t')
 		} else {
-			buffer.WriteByte(c)
+			buffer.WriteRune(r)
 		}
 	}
 	return buffer.String()
diff --git a/test/cases/io-spec-tsv/0003/cmd b/test/cases/io-spec-tsv/0003/cmd
new file mode 100644
index 000000000..2819081d3
--- /dev/null
+++ b/test/cases/io-spec-tsv/0003/cmd
@@ -0,0 +1 @@
+mlr --ijson --otsv cat ${CASEDIR}/data.json
diff --git a/test/cases/io-spec-tsv/0003/data.json b/test/cases/io-spec-tsv/0003/data.json
new file mode 100644
index 000000000..55dbdbc47
--- /dev/null
+++ b/test/cases/io-spec-tsv/0003/data.json
@@ -0,0 +1,7 @@
+[
+{
+  "alpha": "alpha",
+  "βετα": "βετα",
+  "гамма": "гамма"
+}
+]
diff --git a/test/cases/io-spec-tsv/0003/experr b/test/cases/io-spec-tsv/0003/experr
new file mode 100644
index 000000000..e69de29bb
diff --git a/test/cases/io-spec-tsv/0003/expout b/test/cases/io-spec-tsv/0003/expout
new file mode 100644
index 000000000..30d3cbb6a
--- /dev/null
+++ b/test/cases/io-spec-tsv/0003/expout
@@ -0,0 +1,2 @@
+alpha	βετα	гамма
+alpha	βετα	гамма