diff --git a/src/util/test/text-codec.c b/src/util/test/text-codec.c
index 537492d06..75e382f8c 100644
--- a/src/util/test/text-codec.c
+++ b/src/util/test/text-codec.c
@@ -42,7 +42,7 @@ M_TEST_DEFINE(singleEntry) {
 
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 0x41, output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
@@ -51,7 +51,7 @@ M_TEST_DEFINE(singleEntry) {
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 0x41, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
 	assert_memory_equal(output, "B", 1);
@@ -59,7 +59,7 @@ M_TEST_DEFINE(singleEntry) {
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 0x41, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 0x41, output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
@@ -95,7 +95,7 @@ M_TEST_DEFINE(singleEntryReverse) {
 
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 'B', output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
@@ -104,7 +104,7 @@ M_TEST_DEFINE(singleEntryReverse) {
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'B', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
 	assert_memory_equal(output, "A", 1);
@@ -112,7 +112,7 @@ M_TEST_DEFINE(singleEntryReverse) {
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'B', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 'B', output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
@@ -181,7 +181,7 @@ M_TEST_DEFINE(twoEntry) {
 
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 0x41, output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
@@ -189,7 +189,7 @@ M_TEST_DEFINE(twoEntry) {
 
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 0x43, output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
@@ -198,7 +198,7 @@ M_TEST_DEFINE(twoEntry) {
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 0x41, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
 	assert_memory_equal(output, "B", 1);
@@ -206,7 +206,7 @@ M_TEST_DEFINE(twoEntry) {
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 0x43, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 0x42, output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
 	assert_memory_equal(output, "D", 1);
@@ -274,7 +274,7 @@ M_TEST_DEFINE(longEntry) {
 
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
@@ -282,7 +282,7 @@ M_TEST_DEFINE(longEntry) {
 
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 2, output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
@@ -291,7 +291,7 @@ M_TEST_DEFINE(longEntry) {
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
 	assert_memory_equal(output, "Ab", 2);
@@ -299,7 +299,7 @@ M_TEST_DEFINE(longEntry) {
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 2, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
 	assert_memory_equal(output, "cd", 2);
@@ -377,7 +377,7 @@ M_TEST_DEFINE(longEntryReverse) {
 
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
@@ -386,7 +386,7 @@ M_TEST_DEFINE(longEntryReverse) {
 
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 'c', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
@@ -396,8 +396,8 @@ M_TEST_DEFINE(longEntryReverse) {
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len), -1);
+	assert_int_equal(TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 0);
 
@@ -405,7 +405,7 @@ M_TEST_DEFINE(longEntryReverse) {
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
 	assert_memory_equal(output, "\1", 1);
@@ -413,8 +413,8 @@ M_TEST_DEFINE(longEntryReverse) {
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'c', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len), -1);
+	assert_int_equal(TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 0);
 
@@ -422,7 +422,7 @@ M_TEST_DEFINE(longEntryReverse) {
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'c', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'e', output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 1);
 	assert_memory_equal(output, "\2", 1);
@@ -454,7 +454,7 @@ M_TEST_DEFINE(overlappingEntry) {
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 0xFF, output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
 	assert_memory_equal(output, "Ab", 2);
@@ -471,7 +471,7 @@ M_TEST_DEFINE(overlappingEntry) {
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 0xFF, output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 2, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 2, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 2, output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
 	assert_memory_equal(output, "Ac", 2);
@@ -518,7 +518,7 @@ M_TEST_DEFINE(overlappingEntry) {
 
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 0xFF, output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
@@ -528,15 +528,15 @@ M_TEST_DEFINE(overlappingEntry) {
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 0xFF, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len), -1);
+	assert_int_equal(TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 0);
 
 	len = 0;
 	TextCodecStartDecode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 0xFF, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 0xFF, output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
@@ -548,7 +548,7 @@ M_TEST_DEFINE(overlappingEntry) {
 	len += TextCodecAdvance(&iter, 0xFF, output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 1, output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 0xFF, output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 3, output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
 	assert_memory_equal(output, "Ab", 2);
@@ -580,7 +580,7 @@ M_TEST_DEFINE(overlappingEntryReverse) {
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
 	assert_memory_equal(output, "\xFF\1", 2);
@@ -597,7 +597,7 @@ M_TEST_DEFINE(overlappingEntryReverse) {
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'c', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'c', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'c', output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
 	assert_memory_equal(output, "\xFF\2", 2);
@@ -644,7 +644,7 @@ M_TEST_DEFINE(overlappingEntryReverse) {
 
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
-	len += TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
@@ -654,15 +654,15 @@ M_TEST_DEFINE(overlappingEntryReverse) {
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len), -1);
+	assert_int_equal(TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 0);
 
 	len = 0;
 	TextCodecStartEncode(&codec, &iter);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len), -1);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
@@ -674,7 +674,7 @@ M_TEST_DEFINE(overlappingEntryReverse) {
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'b', output + len, sizeof(output) - len);
 	len += TextCodecAdvance(&iter, 'A', output + len, sizeof(output) - len);
-	len += TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len);
+	assert_int_equal(TextCodecAdvance(&iter, 'd', output + len, sizeof(output) - len), -1);
 	len += TextCodecFinish(&iter, output + len, sizeof(output) - len);
 	assert_int_equal(len, 2);
 	assert_memory_equal(output, "\xFF\1", 2);
diff --git a/src/util/text-codec.c b/src/util/text-codec.c
index dfb94a4e6..399016f59 100644
--- a/src/util/text-codec.c
+++ b/src/util/text-codec.c
@@ -146,18 +146,18 @@ void TextCodecStartEncode(struct TextCodec* codec, struct TextCodecIterator* ite
 	iter->current = iter->root;
 }
 
-static size_t _TextCodecFinishInternal(struct TextCodecNode* node, uint8_t* output, size_t outputLength) {
+static ssize_t _TextCodecFinishInternal(struct TextCodecNode* node, uint8_t* output, size_t outputLength) {
 	if (outputLength > node->leafLength) {
 		outputLength = node->leafLength;
 	}
 	if (node->leafLength == 0) {
-		return 0;
+		return -1;
 	}
 	memcpy(output, node->leaf, outputLength);
 	return node->leafLength;
 }
 
-size_t TextCodecAdvance(struct TextCodecIterator* iter, uint8_t byte, uint8_t* output, size_t outputLength) {
+ssize_t TextCodecAdvance(struct TextCodecIterator* iter, uint8_t byte, uint8_t* output, size_t outputLength) {
 	struct TextCodecNode* node = TableLookup(&iter->current->children, byte);
 	if (!node) {
 		ssize_t size = _TextCodecFinishInternal(iter->current, output, outputLength);
@@ -170,17 +170,28 @@ size_t TextCodecAdvance(struct TextCodecIterator* iter, uint8_t byte, uint8_t* o
 			return size;
 		}
 		if (iter->current == iter->root) {
-			return 0;
+			return -1;
 		}
 		iter->current = iter->root;
-		return TextCodecAdvance(iter, byte, output, outputLength) + size;
+		ssize_t newSize = TextCodecAdvance(iter, byte, output, outputLength);
+		if (newSize < 0 && size > 0) {
+			return size;
+		}
+		return newSize + size;
+	}
+	if (TableSize(&node->children) == 0) {
+		iter->current = iter->root;
+		return _TextCodecFinishInternal(node, output, outputLength);
 	}
 	iter->current = node;
 	return 0;
 }
 
-size_t TextCodecFinish(struct TextCodecIterator* iter, uint8_t* output, size_t outputLength) {
+ssize_t TextCodecFinish(struct TextCodecIterator* iter, uint8_t* output, size_t outputLength) {
 	struct TextCodecNode* node = iter->current;
 	iter->current = iter->root;
+	if (node->leafLength == 0) {
+		return 0;
+	}
 	return _TextCodecFinishInternal(node, output, outputLength);
 }
diff --git a/src/util/text-codec.h b/src/util/text-codec.h
index df265861c..e17436c7b 100644
--- a/src/util/text-codec.h
+++ b/src/util/text-codec.h
@@ -26,7 +26,7 @@ void TextCodecDeinit(struct TextCodec*);
 void TextCodecStartDecode(struct TextCodec*, struct TextCodecIterator*);
 void TextCodecStartEncode(struct TextCodec*, struct TextCodecIterator*);
 
-size_t TextCodecAdvance(struct TextCodecIterator*, uint8_t byte, uint8_t* output, size_t outputLength);
-size_t TextCodecFinish(struct TextCodecIterator*, uint8_t* output, size_t outputLength);
+ssize_t TextCodecAdvance(struct TextCodecIterator*, uint8_t byte, uint8_t* output, size_t outputLength);
+ssize_t TextCodecFinish(struct TextCodecIterator*, uint8_t* output, size_t outputLength);
 
 #endif