diff --git a/src/Zinc-Character-Encoding-Core/ZnBufferedReadStream.class.st b/src/Zinc-Character-Encoding-Core/ZnBufferedReadStream.class.st
index adda150..00f16bc 100644
--- a/src/Zinc-Character-Encoding-Core/ZnBufferedReadStream.class.st
+++ b/src/Zinc-Character-Encoding-Core/ZnBufferedReadStream.class.st
@@ -403,13 +403,12 @@ ZnBufferedReadStream >> uint8 [
 { #category : 'accessing' }
 ZnBufferedReadStream >> upTo: value [ 
 	"Read upto but not including value and return them as a collection.
-	If value is not found, return the entire contents of the stream.
-	This could be further optimzed."
+	If value is not found, return the entire contents of the stream."
 	
 	^ self collectionSpecies 
-		streamContents: [ :writeStream |
-			[ self atEnd or: [ (self peek) = value ] ] whileFalse: [ 
-				writeStream nextPut: self next ] ]
+		streamContents: [ :writeStream | | ch |
+			[ self atEnd or: [ (ch := self next) = value ] ] whileFalse: [ 
+				writeStream nextPut: ch ] ]
 ]
 
 { #category : 'accessing' }
@@ -421,9 +420,12 @@ aCollection isEmpty ifTrue: [ ^aCollection ].
 startPos := self position.
 "upTo: will stop before aCollection first"
 x := self upTo: aCollection first.
-(self atEnd or: [aCollection size = 1 ])
-	ifTrue: [ ^ x ].
-self next. "move past the matching char from upTo:"
+self atEnd
+	ifTrue: [ 
+		aCollection size <= 1
+			ifTrue: [ ^ x ].
+		self position: startPos.
+		^ self upToEnd].
 2 to: aCollection size do: [:i | | y |
 	(y := self peek) = (aCollection at: i)
 		ifTrue: [ self next ]
diff --git a/src/Zinc-Character-Encoding-Tests/ZnCharacterStreamTests.class.st b/src/Zinc-Character-Encoding-Tests/ZnCharacterStreamTests.class.st
index 7a50bbf..aba8dca 100644
--- a/src/Zinc-Character-Encoding-Tests/ZnCharacterStreamTests.class.st
+++ b/src/Zinc-Character-Encoding-Tests/ZnCharacterStreamTests.class.st
@@ -112,6 +112,18 @@ ZnCharacterStreamTests >> testReadStream [
 	self assert: stream peek isNil
 ]
 
+{ #category : 'testing' }
+ZnCharacterStreamTests >> testReadUpTo [
+	| string |
+	string := '0123456789'.
+	{(self eightBitReadStreamOn: string).
+	(self utf8ReadStreamOn: string)}
+		do: [ :stream | 
+			self assert: (stream upTo: $5) equals: '01234'.
+			self assert: stream upToEnd equals: '6789'.
+			self assert: stream atEnd ]
+]
+
 { #category : 'testing' }
 ZnCharacterStreamTests >> testSimpleUTF8ReadStream [
 	| string bytes stream |
@@ -136,18 +148,6 @@ ZnCharacterStreamTests >> testSimpleUTF8WriteStream [
 		equals: bytes asByteArray
 ]
 
-{ #category : 'testing' }
-ZnCharacterStreamTests >> testUtf8EncodingStreamPosition [
-	| string bytes stream res |
-	string := 'eißendeße'.
-	bytes := ZnUTF8Encoder new encodeString: string.
-	stream := (ZnCharacterReadStream on: bytes readStreamPortable).
-	res := stream next; next; next.
-	self assert: res equals: $ß.
-	self assert: stream position equals: 3.
-	
-]
-
 { #category : 'testing' }
 ZnCharacterStreamTests >> testUpTo [
 	| char1 char2 string1 string2 |
@@ -206,6 +206,22 @@ ZnCharacterStreamTests >> testUpTo [
 ZnCharacterStreamTests >> testUpToAll [
 	#(
 		('' '' '')
+		('a' '' '')
+		('a' 'a' '')
+		('a' 'b' 'a')
+		('ab' '' '')
+		('ab' 'a' '')
+		('ab' 'b' 'a')
+		('ab' 'c' 'ab')
+		('ab' 'ab' '')
+		('abc' '' '')
+		('abc' 'a' '')
+		('abc' 'b' 'a')
+		('abc' 'c' 'ab')
+		('abc' 'd' 'abc')
+		('abc' 'ab' '')
+		('abc' 'bc' 'a')
+		('abc' 'cd' 'abc')
 		('' 'ß' '')
 		('' 'ße' '')
 		('ß' '' '')
@@ -228,22 +244,6 @@ ZnCharacterStreamTests >> testUpToAll [
 		('eißen' 'ßend' 'eißen')
 		('eißendeße' 'ße' 'ei')
 		('abcdefgh' 'cd' 'ab')
-		('a' '' '')
-		('a' 'a' '')
-		('a' 'b' 'a')
-		('ab' '' '')
-		('ab' 'a' '')
-		('ab' 'b' 'a')
-		('ab' 'c' 'ab')
-		('ab' 'ab' '')
-		('abc' '' '')
-		('abc' 'a' '')
-		('abc' 'b' 'a')
-		('abc' 'c' 'ab')
-		('abc' 'd' 'abc')
-		('abc' 'ab' '')
-		('abc' 'bc' 'a')
-		('abc' 'cd' 'abc')
 	) do: [ :array | self assertUpToAll: array ]
 ]
 
@@ -272,6 +272,30 @@ ZnCharacterStreamTests >> testUpToAllTwice [
 
 ]
 
+{ #category : 'testing' }
+ZnCharacterStreamTests >> test8BitEncodingStreamPosition [
+	| string bytes stream res |
+	string := 'eiSendeSe'.
+	bytes := Zn8BITEncoder new encodeString: string.
+	stream := (ZnCharacterReadStream on: bytes readStreamPortable).
+	res := stream next; next; next.
+	self assert: res equals: $S.
+	self assert: stream position equals: 3.
+	
+]
+
+{ #category : 'testing' }
+ZnCharacterStreamTests >> testUtf8EncodingStreamPosition [
+	| string bytes stream res |
+	string := 'eißendeße'.
+	bytes := ZnUTF8Encoder new encodeString: string.
+	stream := (ZnCharacterReadStream on: bytes readStreamPortable).
+	res := stream next; next; next.
+	self assert: res equals: $ß.
+	self assert: stream position equals: 3.
+	
+]
+
 { #category : 'testing' }
 ZnCharacterStreamTests >> testUTF8ReadStreamReadInto [
 	| string bytes stream buffer |