diff --git a/StgScala/acn_scala.stg b/StgScala/acn_scala.stg
index 12b5ca23c..872875aff 100644
--- a/StgScala/acn_scala.stg
+++ b/StgScala/acn_scala.stg
@@ -1,6 +1,6 @@
 group scala_acn;
 
-getStringSize(p) ::= "ULong.fromRaw(<p>.indexOf(0x00.toRawUByte))"
+getStringSize(p) ::= "ULong.fromRaw(<p>.indexOfOrLength(0x00.toRawUByte))"
 
 getSizeableSize(p, sAcc, bIsUnsigned) ::= <<
 <if(bIsUnsigned)>
@@ -450,11 +450,11 @@ val <p> = codec.dec_String_Ascii_FixSize(<nAsn1Max>)
 >>
 
 Acn_String_Ascii_Null_Terminated_encode(p, sErrCode, nAsn1Max, arruNullBytes) ::= <<
-codec.enc_String_Ascii_Null_Terminated_mult(<nAsn1Max>, Array({<arruNullBytes; separator=", ">}), <arruNullBytes.Length>, <p>)
+codec.enc_String_Ascii_Null_Terminated_multVec(<nAsn1Max>, Array({<arruNullBytes; separator=", ">}), <arruNullBytes.Length>, <p>)
 >>
 
 Acn_String_Ascii_Null_Terminated_decode(p, sErrCode, nAsn1Max, arruNullBytes) ::= <<
-val <p> = codec.dec_String_Ascii_Null_Terminated_mult(<nAsn1Max>, Array({<arruNullBytes; separator=", ">}), <arruNullBytes.Length>)
+val <p> = codec.dec_String_Ascii_Null_Terminated_multVec(<nAsn1Max>, Array({<arruNullBytes; separator=", ">}), <arruNullBytes.Length>)
 >>
 
 Acn_String_Ascii_External_Field_Determinant_encode(p, sErrCode, nAsn1Max, sExtFld) ::= "codec.enc_String_Ascii_External_Field_Determinant(<nAsn1Max>, <p>)"
@@ -625,7 +625,7 @@ val <p> =
 
 oct_sqf_null_terminated_encode(p, sAcc, i, sInternalItem, noSizeMin, nSizeMax, arruNullBytes, nBitPatternLength, sErrCode, nIntItemMinSize, nIntItemMaxSize) ::= <<
 <loopFixedItem(i=i, sInternalItem=sInternalItem, fixedSize=[p, sAcc, "nCount"])>
-codec.base.bitStream.appendBitsMSBFirst(Array({<arruNullBytes; separator=", ">}), <nBitPatternLength>)
+codec.base.bitStream.appendBitsMSBFirstVec(Array({<arruNullBytes; separator=", ">}), <nBitPatternLength>)
 >>
 
 oct_sqf_null_terminated_decode(p, sAcc, i, sInternalItem, noSizeMin, nSizeMax, arruNullBytes, nBitPatternLength, sErrCode, nIntItemMinSize, nIntItemMaxSize) ::= <<
@@ -648,7 +648,7 @@ else if checkBitPatternPresentResult.get then
 >>
 
 bit_string_external_field_encode(sTypeDefName, p, sErrCode, sAcc, noSizeMin, nSizeMax, sExtFld) ::= <<
-codec.base.bitStream.appendBitsMSBFirst(<p><sAcc>arr, <p><sAcc>nCount)
+codec.base.bitStream.appendBitsMSBFirstVec(<p><sAcc>arr, <p><sAcc>nCount)
 >>
 
 bit_string_external_field_decode(sTypeDefName, p, sErrCode, sAcc, noSizeMin, nSizeMax, sExtFld) ::= <<
@@ -659,7 +659,7 @@ val <p> =
 >>
 
 bit_string_external_field_fixed_size_encode(sTypeDefName, p, sErrCode, sAcc, noSizeMin, nSizeMax, sExtFld) ::= <<
-codec.base.bitStream.appendBitsMSBFirst(<p><sAcc>arr, <nSizeMax>)
+codec.base.bitStream.appendBitsMSBFirstVec(<p><sAcc>arr, <nSizeMax>)
 >>
 
 bit_string_external_field_fixed_size_decode(sTypeDefName, p, sErrCode, sAcc, noSizeMin, nSizeMax, sExtFld) ::= <<
@@ -670,7 +670,7 @@ val <p> =
 >>
 
 bit_string_null_terminated_encode(sTypeDefName, p, sErrCode, sAcc, i, noSizeMin, nSizeMax, arruNullBytes, nBitPatternLength) ::= <<
-codec.base.bitStream.appendBitsMSBFirst(<p><sAcc>arr, <p><sAcc>arr.length*8) // TODO: re-introduce nCount?  -> codec.base.bitStream.appendBitsMSBFirst(<p><sAcc>arr, <p><sAcc>nCount)
+codec.base.bitStream.appendBitsMSBFirstVec(<p><sAcc>arr, <p><sAcc>arr.length*8) // TODO: re-introduce nCount?  -> codec.base.bitStream.appendBitsMSBFirst(<p><sAcc>arr, <p><sAcc>nCount)
 codec.base.bitStream.appendBitsMSBFirst(Array({<arruNullBytes; separator=", ">}), <nBitPatternLength>)
 >>
 
@@ -1078,7 +1078,7 @@ octet_string_containing_ext_field_func_decode(p, sFuncName, sReqBytesForUperEnco
 >>
 
 bit_string_containing_ext_field_func_encode(p, sFuncName, sReqBytesForUperEncoding, sReqBitsForUperEncoding, sExtField, sErrCode) ::= <<
-codec.base.bitStream.appendBitsMSBFirst(arr, <sExtField>.toInt)
+codec.base.bitStream.appendBitsMSBFirstVec(arr, <sExtField>.toInt)
 >>
 
 bit_string_containing_ext_field_func_decode(p, sFuncName, sReqBytesForUperEncoding, sReqBitsForUperEncoding, sExtField, sErrCode) ::= <<
diff --git a/StgScala/equal_scala.stg b/StgScala/equal_scala.stg
index c72920981..627818a37 100644
--- a/StgScala/equal_scala.stg
+++ b/StgScala/equal_scala.stg
@@ -78,7 +78,12 @@ def <sFuncName>(<sVarName1>: <sTypeDefName>, <sVarName2>: <sTypeDefName>): Boole
 
 isEqual_Primitive(p1, p2) ::= "<p1> == <p2>"
 
-isEqual_String(p1, p2) ::= "<p1>.toScala.sameElements(<p2>.toScala)"
+isEqual_String(p1, p2) ::= <<
+locally {
+    val zero = <p1>.indexOfOrLength(UByte.fromRaw(0))
+    <p1>.toScala.slice(0, zero).sameElements(<p2>.toScala.slice(0, zero))
+}
+>>
 
 
 isEqual_Integer(p1, p2) /*nogen*/::= "ret = (<p1> == <p2>)"
@@ -90,7 +95,12 @@ isEqual_Boolean(p1, p2) /*nogen*/::= "ret = ( (<p1> && <p2>) || (!<p1> && !<p2>)
 
 isEqual_Real(p1, p2) ::= "Asn1Real_Equal(<p1>, <p2>)"
 
-isEqual_IA5String(p1, p2) /*nogen*/::= "ret = <p1>.toScala.sameElements(<p2>.toScala)"
+isEqual_IA5String(p1, p2) /*nogen*/::= <<
+locally {
+    val zero = <p1>.indexOfOrLength(UByte.fromRaw(0))
+    ret = <p1>.toScala.slice(0, zero).sameElements(<p2>.toScala.slice(0, zero))
+}
+>>
 
 isEqual_NumericString(p1, p2) /*nogen*/::= "<isEqual_IA5String(p1=p1, p2=p2)>"
 isEqual_NullType()/*nogen*/ ::= "ret = true"
diff --git a/StgScala/init_scala.stg b/StgScala/init_scala.stg
index 5b86c9147..23c7bc0cd 100644
--- a/StgScala/init_scala.stg
+++ b/StgScala/init_scala.stg
@@ -119,11 +119,11 @@ val <sResVar> = Vector.fill(<nMaxSizePlusOne>)(UByte.fromRaw(0))
 <else>
 <if(bAlpha)>
 val allowedCharSet: Array[UByte] = Array(<arrnAlphabetAsciiCodes:{ch|0x<ch;format="X2">.toRawUByte}; wrap, anchor, separator=",">)
-val <sResVar>_tmp = scala.collection.immutable.Vector.tabulate(<nMaxSizePlusOne>)(<i> => if <i> == <nMaxSizePlusOne> - 1 then 0.toByte else allowedCharSet(<i> % <nAlphabetLength>))
-val <sResVar> = Vector.fromScala(<sResVar>_tmp)
+val <sResVar>_tmp = scala.collection.immutable.Vector.tabulate(<nSize>)(<i> => if <i> == <nMaxSizePlusOne> - 1 then UByte.fromRaw(0) else allowedCharSet(<i> % <nAlphabetLength>))
+val <sResVar> = Vector.fromScala(<sResVar>_tmp :+ UByte.fromRaw(0))
 <else>
-val <sResVar>_tmp = scala.collection.immutable.Vector.tabulate(<nMaxSizePlusOne>)(<i> => UByte.fromRaw(if <i> == <nMaxSizePlusOne> - 1 then 0.toByte else if <i> % 128 == 0 then 'A'.toByte else (<i> % 128).toByte))
-val <sResVar> = Vector.fromScala(<sResVar>_tmp)
+val <sResVar>_tmp = scala.collection.immutable.Vector.tabulate(<nSize>)(<i> => UByte.fromRaw(if <i> == <nMaxSizePlusOne> - 1 then 0.toByte else if <i> % 128 == 0 then 'A'.toByte else (<i> % 128).toByte))
+val <sResVar> = Vector.fromScala(<sResVar>_tmp :+ UByte.fromRaw(0))
 <endif>
 <endif>
 >>
diff --git a/StgScala/isvalid_scala.stg b/StgScala/isvalid_scala.stg
index dcad543fa..e6062b18d 100644
--- a/StgScala/isvalid_scala.stg
+++ b/StgScala/isvalid_scala.stg
@@ -187,9 +187,9 @@ StatementForLoop(p, sAcc, i, bIsFixedSize, nFixedSize, sInnerStatement) ::= <<
 
 
 Print_AlphabetCheckFunc(sFuncName, arrsAlphaConBody) ::= <<
-def <sFuncName>(str0: Array[UByte]): Boolean =
+def <sFuncName>(str0: Vector[UByte]): Boolean =
 {
-    val str = str0.toArrayRaws
+    val str = str0.toVectorRaws
     var valid: Boolean = true
     var i: Int = 0
     (while (i \< str.length && (str(i) != CHAR_0000) && valid) {
diff --git a/StgScala/uper_scala.stg b/StgScala/uper_scala.stg
index 66eb9410b..57d650a9a 100644
--- a/StgScala/uper_scala.stg
+++ b/StgScala/uper_scala.stg
@@ -431,7 +431,7 @@ str_FixedSize_decode(p, sTasName, i, sInternalItem, nFixedSize, nIntItemMinSize,
 
 
 str_VarSize_encode(p, sPIden, sTasName, i, sInternalItem, nSizeMin, nSizeMax, nSizeInBits, nIntItemMinSize, nIntItemMaxSize, nAlignSize, soInitExpr, soCallAux) ::= <<
-nStringLength = <p>.indexOf(0x00.toRawUByte)
+nStringLength = <p>.indexOfOrLength(0x00.toRawUByte)
 /*ret = nStringLength >= <nSizeMin> && nStringLength \<= <nSizeMax>;*/
 codec.base.encodeConstrainedWholeNumber(nStringLength, <nSizeMin>, <nSizeMax>)
 val <sPIden>_nCount = nStringLength
diff --git a/asn1scala/src/main/scala/asn1scala/asn1jvm_Codec_ACN.scala b/asn1scala/src/main/scala/asn1scala/asn1jvm_Codec_ACN.scala
index b33663e40..356335299 100644
--- a/asn1scala/src/main/scala/asn1scala/asn1jvm_Codec_ACN.scala
+++ b/asn1scala/src/main/scala/asn1scala/asn1jvm_Codec_ACN.scala
@@ -1505,6 +1505,10 @@ case class ACN(base: Codec) {
          i += 1
    }
 
+   def enc_String_Ascii_Null_Terminated_multVec(max: Long, null_character: Array[Byte], null_character_size: Int, strVal: Vector[ASCIIChar]): Unit = {
+      enc_String_Ascii_Null_Terminated_mult(max, null_character, null_character_size, strVal.toScala.toArray)
+   }
+
 
    def enc_String_Ascii_External_Field_Determinant(max: Long, strVal: Array[ASCIIChar]): Unit = {
       enc_String_Ascii_private(max, strVal)
@@ -1690,6 +1694,10 @@ case class ACN(base: Codec) {
       strVal
    }
 
+   def dec_String_Ascii_Null_Terminated_multVec(max: Long, null_character: Array[ASCIIChar], null_character_size: Int): Vector[ASCIIChar] = {
+      val res = dec_String_Ascii_Null_Terminated_mult(max, null_character, null_character_size)
+      Vector.fromScala(res.toVector)
+   }
 
    @opaque @inlineOnce
    def dec_String_Ascii_External_Field_Determinant(max: Long, extSizeDeterminantFld: Long): Array[ASCIIChar] = {