diff --git a/saddle-io/src/main/scala/org/saddle/io/csv/DataBuffer.scala b/saddle-io/src/main/scala/org/saddle/io/csv/DataBuffer.scala
index b0a1bba8..d776f2a5 100644
--- a/saddle-io/src/main/scala/org/saddle/io/csv/DataBuffer.scala
+++ b/saddle-io/src/main/scala/org/saddle/io/csv/DataBuffer.scala
@@ -1136,6 +1136,7 @@ private[csv] final class DataBuffer1(
   private var outputChars: Array[Char] = null
 
   // -2 means quote unclosed
+  // -1 means initial value
   private var outputLength = -1
 
   private val outputFrom = Array.ofDim[Int](bufferSize + 2)
@@ -1183,77 +1184,83 @@ private[csv] final class DataBuffer1(
     } else ((outputChars, outputFrom, outputTo, outputLength))
 
   private def fillBuffer(): Boolean = {
-    if (!data.hasNext) false
-    else {
-      filledNewData = true
+    if (!data.hasNext) {
+      false
+    } else {
       val next = data.next()
-
-      quoteMask.zero()
-      lfMask.zero()
-      fieldSeparatorMask.zero()
-
-      if (commonCSV)
-        elementWiseEqual3CSV_LF(
-          a = next,
-          o1 = quoteMask,
-          o2 = lfMask,
-          o3 = fieldSeparatorMask
-        )
-      else if (commonTSV)
-        elementWiseEqual3TSV(
-          a = next,
-          o1 = quoteMask,
-          o2 = lfMask,
-          o3 = fieldSeparatorMask
-        )
-      else
-        elementWiseEqual3Variable(
-          a = next,
-          t1 = quoteChar,
-          o1 = quoteMask,
-          t2 = recordSeparator,
-          o2 = lfMask,
-          t3 = fieldSeparator,
-          o3 = fieldSeparatorMask
+      if (!next.hasRemaining()) {
+        outputLength = 0
+        true
+      } else {
+        filledNewData = true
+
+        quoteMask.zero()
+        lfMask.zero()
+        fieldSeparatorMask.zero()
+
+        if (commonCSV)
+          elementWiseEqual3CSV_LF(
+            a = next,
+            o1 = quoteMask,
+            o2 = lfMask,
+            o3 = fieldSeparatorMask
+          )
+        else if (commonTSV)
+          elementWiseEqual3TSV(
+            a = next,
+            o1 = quoteMask,
+            o2 = lfMask,
+            o3 = fieldSeparatorMask
+          )
+        else
+          elementWiseEqual3Variable(
+            a = next,
+            t1 = quoteChar,
+            o1 = quoteMask,
+            t2 = recordSeparator,
+            o2 = lfMask,
+            t3 = fieldSeparator,
+            o3 = fieldSeparatorMask
+          )
+
+        val nInQuote: BitSet = prefixSumXor(quoteMask)
+        nInQuote.negateInplace()
+
+        val (structuralMask: BitSet, recordSeparatorMask: BitSet) = {
+
+          lfMask &= nInQuote
+          fieldSeparatorMask &= nInQuote
+
+          val structuralMask = lfMask | fieldSeparatorMask
+
+          (structuralMask, lfMask)
+        }
+        outputChars = next.array()
+        assert(next.arrayOffset() == 0)
+        outputLength = toIndices1(
+          chars = next,
+          structuralMask = structuralMask,
+          recordSeparatorMask = recordSeparatorMask,
+          quoteMask = quoteMask,
+          from = outputFrom,
+          to = outputTo
         )
 
-      val nInQuote: BitSet = prefixSumXor(quoteMask)
-      nInQuote.negateInplace()
-
-      val (structuralMask: BitSet, recordSeparatorMask: BitSet) = {
-
-        lfMask &= nInQuote
-        fieldSeparatorMask &= nInQuote
-
-        val structuralMask = lfMask | fieldSeparatorMask
-
-        (structuralMask, lfMask)
-      }
-      outputChars = next.array()
-      assert(next.arrayOffset() == 0)
-      outputLength = toIndices1(
-        chars = next,
-        structuralMask = structuralMask,
-        recordSeparatorMask = recordSeparatorMask,
-        quoteMask = quoteMask,
-        from = outputFrom,
-        to = outputTo
-      )
+        if (recordSeparatorMask.contains(next.limit() - 1)) {
+          lineClosed = true
+        } else {
+          lineClosed = false
+        }
 
-      if (recordSeparatorMask.contains(next.limit() - 1)) {
-        lineClosed = true
-      } else {
-        lineClosed = false
-      }
+        if (next.position() == 0 && lastPos == 0) {
+          bufferTooShort = true
+          false
+        } else {
+          lastPos = next.position()
+          true
+        }
 
-      if (next.position() == 0 && lastPos == 0) {
-        bufferTooShort = true
-        false
-      } else {
-        lastPos = next.position()
-        true
       }
-
     }
   }
 
@@ -1319,76 +1326,81 @@ private[csv] final class DataBuffer2(
   private def fillBuffer(): Boolean = {
     if (!data.hasNext) false
     else {
-      filledNewData = true
       val next = data.next()
+      if (!next.hasRemaining()) {
+        outputLength = 0
+        true
+      } else {
+        filledNewData = true
+
+        quoteMask.zero()
+        crMask.zero()
+        lfMask.zero()
+        fieldSeparatorMask.zero()
+
+        if (rfcCompatible)
+          elementWiseEqual4RFC(
+            a = next,
+            o1 = quoteMask,
+            o2 = lfMask,
+            o3 = crMask,
+            o4 = fieldSeparatorMask
+          )
+        else
+          elementWiseEqual4Variable(
+            a = next,
+            t1 = quoteChar,
+            o1 = quoteMask,
+            t2 = recordSeparator2,
+            o2 = lfMask,
+            t3 = recordSeparator1,
+            o3 = crMask,
+            t4 = fieldSeparator,
+            o4 = fieldSeparatorMask
+          )
+
+        val nInQuote: BitSet = prefixSumXor(quoteMask)
+        nInQuote.negateInplace()
+
+        val (structuralMask: BitSet, recordSeparatorMask: BitSet) = {
+
+          crMask &= nInQuote
+          lfMask &= nInQuote
+          fieldSeparatorMask &= nInQuote
+
+          // overwrites crMask
+          makeMaskFromCrLfInPlace(crMask, lfMask)
+          val structuralMask = crMask | fieldSeparatorMask
+
+          (structuralMask, crMask)
 
-      quoteMask.zero()
-      crMask.zero()
-      lfMask.zero()
-      fieldSeparatorMask.zero()
-
-      if (rfcCompatible)
-        elementWiseEqual4RFC(
-          a = next,
-          o1 = quoteMask,
-          o2 = lfMask,
-          o3 = crMask,
-          o4 = fieldSeparatorMask
-        )
-      else
-        elementWiseEqual4Variable(
-          a = next,
-          t1 = quoteChar,
-          o1 = quoteMask,
-          t2 = recordSeparator2,
-          o2 = lfMask,
-          t3 = recordSeparator1,
-          o3 = crMask,
-          t4 = fieldSeparator,
-          o4 = fieldSeparatorMask
+        }
+        outputChars = next.array()
+        assert(next.arrayOffset() == 0)
+        outputLength = toIndices2(
+          chars = next,
+          structuralMask = structuralMask,
+          recordSeparatorMask = recordSeparatorMask,
+          quoteMask = quoteMask,
+          from = outputFrom,
+          to = outputTo
         )
 
-      val nInQuote: BitSet = prefixSumXor(quoteMask)
-      nInQuote.negateInplace()
-
-      val (structuralMask: BitSet, recordSeparatorMask: BitSet) = {
-
-        crMask &= nInQuote
-        lfMask &= nInQuote
-        fieldSeparatorMask &= nInQuote
-
-        // overwrites crMask
-        makeMaskFromCrLfInPlace(crMask, lfMask)
-        val structuralMask = crMask | fieldSeparatorMask
-
-        (structuralMask, crMask)
-
-      }
-      outputChars = next.array()
-      assert(next.arrayOffset() == 0)
-      outputLength = toIndices2(
-        chars = next,
-        structuralMask = structuralMask,
-        recordSeparatorMask = recordSeparatorMask,
-        quoteMask = quoteMask,
-        from = outputFrom,
-        to = outputTo
-      )
+        if (recordSeparatorMask.contains(next.limit() - 1)) {
+          lineClosed = true
+        } else {
+          lineClosed = false
+        }
 
-      if (recordSeparatorMask.contains(next.limit() - 1)) {
-        lineClosed = true
-      } else {
-        lineClosed = false
-      }
+        if (next.position() == 0 && lastPos == 0) {
+          bufferTooShort = true
+          false
+        } else {
+          lastPos = next.position()
+          true
+        }
 
-      if (next.position() == 0 && lastPos == 0) {
-        bufferTooShort = true
-        false
-      } else {
-        lastPos = next.position()
-        true
       }
-
     }
   }
 
diff --git a/saddle-io/src/main/scala/org/saddle/io/csv/package.scala b/saddle-io/src/main/scala/org/saddle/io/csv/package.scala
index c2e80c69..1fbfd66c 100644
--- a/saddle-io/src/main/scala/org/saddle/io/csv/package.scala
+++ b/saddle-io/src/main/scala/org/saddle/io/csv/package.scala
@@ -151,7 +151,7 @@ package object csv {
     var eof = false
     var decFlushed = false
     charset.reset()
-    def fillBuffer() = if (!eof) {
+    def fillBuffer(): Unit = if (!eof) {
       var count = channel.read(buffer)
       while (count >= 0 && buffer.remaining > 0) {
         count = channel.read(buffer)
@@ -165,7 +165,8 @@ package object csv {
           s"Decoder error $result, buffer=${format(buffer)}, charbuffer='${charBuffer}'"
         )
       buffer.compact
-      if (count < 0) {
+      if (count < 0 && result == CoderResult.UNDERFLOW) {
+
         eof = true
         val result = charset.flush(charBuffer)
         charBuffer.flip
@@ -177,9 +178,13 @@ package object csv {
 
     } else {
       charBuffer.compact
-      charset.flush(charBuffer)
+      val result = charset.flush(charBuffer)
       charBuffer.flip
-      decFlushed = true
+      if (result == CoderResult.UNDERFLOW) { decFlushed = true }
+      else
+        throw new RuntimeException(
+          s"Decoder flush error or overflow for the second time ($result), buffer=${format(buffer)}, charbuffer='${charBuffer}. If this is an overflow then the caller must provide a larger buffer.'"
+        )
     }
     new Iterator[CharBuffer] {
       def hasNext = !decFlushed
diff --git a/saddle-io/src/test/scala/org/saddle/io/csv/csv.test.scala b/saddle-io/src/test/scala/org/saddle/io/csv/csv.test.scala
index fd0ef747..71457a03 100644
--- a/saddle-io/src/test/scala/org/saddle/io/csv/csv.test.scala
+++ b/saddle-io/src/test/scala/org/saddle/io/csv/csv.test.scala
@@ -96,6 +96,143 @@ class CSVSuite extends AnyFunSuite {
       )
     )
   }
+  test("lf on the 64th") {
+    val lf = "]"
+    val data =
+      s"""key,pivot,value${lf}0,"a","v1"${lf}0,"b","v2"${lf}0,"b","v3"${lf}1,"c","v4   "${lf}2,"a","v5"${lf}0,"c","v6"${lf}3,"d","v7"${lf}"""
+    val src = ByteChannel(data)
+    val buffer = new BufferCallback
+    org.saddle.io.csv.parse(
+      src,
+      buffer,
+      recordSeparator = lf,
+      bufferSize = 128
+    )
+    assert(
+      buffer.toList == List(
+        "key",
+        "pivot",
+        "value",
+        "0",
+        "a",
+        "v1",
+        "0",
+        "b",
+        "v2",
+        "0",
+        "b",
+        "v3",
+        "1",
+        "c",
+        "v4   ",
+        "2",
+        "a",
+        "v5",
+        "0",
+        "c",
+        "v6",
+        "3",
+        "d",
+        "v7"
+      )
+    )
+  }
+  test("lf on buffer break") {
+    0 until 128 foreach { j =>
+      (7 + j) to 128 foreach { i =>
+        val lf = "]"
+        val insert = 0 until j map (_ => ' ') mkString
+
+        val data =
+          s"""key,pivot,value${lf}0,"a","v1"${lf}0,"b","v2"${lf}0,"b","v3"${lf}1,"c","v4$insert"${lf}2,"a","v5"${lf}0,"c","v6"${lf}3,"d","v7"${lf}"""
+        val src = ByteChannel(data)
+        val buffer = new BufferCallback
+        val r = org.saddle.io.csv.parse(
+          src,
+          buffer,
+          recordSeparator = lf,
+          bufferSize = i
+        )
+        assert(r.isEmpty, r.toString)
+
+        assert(
+          buffer.toList == List(
+            "key",
+            "pivot",
+            "value",
+            "0",
+            "a",
+            "v1",
+            "0",
+            "b",
+            "v2",
+            "0",
+            "b",
+            "v3",
+            "1",
+            "c",
+            s"v4$insert",
+            "2",
+            "a",
+            "v5",
+            "0",
+            "c",
+            "v6",
+            "3",
+            "d",
+            "v7"
+          )
+        )
+      }
+    }
+  }
+  test("crlf on buffer break") {
+    0 until 128 foreach { j =>
+      (7 + j) to 128 foreach { i =>
+        val insert = 0 until j map (_ => ' ') mkString
+        val lf = "[]"
+        val data =
+          s"""key,pivot,value${lf}0,"a","v1"${lf}0,"b","v2"${lf}0,"b","v3"${lf}1,"c","v4$insert"${lf}2,"a","v5"${lf}0,"c","v6"${lf}3,"d","v7"${lf}"""
+        val src = ByteChannel(data)
+        val buffer = new BufferCallback
+        val r = org.saddle.io.csv.parse(
+          src,
+          buffer,
+          recordSeparator = lf,
+          bufferSize = i
+        )
+        assert(r.isEmpty, r.toString)
+        assert(
+          buffer.toList == List(
+            "key",
+            "pivot",
+            "value",
+            "0",
+            "a",
+            "v1",
+            "0",
+            "b",
+            "v2",
+            "0",
+            "b",
+            "v3",
+            "1",
+            "c",
+            s"v4$insert",
+            "2",
+            "a",
+            "v5",
+            "0",
+            "c",
+            "v6",
+            "3",
+            "d",
+            "v7"
+          )
+        )
+      }
+    }
+  }
 
   test("single line") {
     val crlf = "[]"