--- a/src/main/java/nl/cwi/monetdb/jdbc/MonetPreparedStatement.java
+++ b/src/main/java/nl/cwi/monetdb/jdbc/MonetPreparedStatement.java
@@ -19,6 +19,7 @@ import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.math.RoundingMode;
 import java.net.URL;
+import java.nio.Buffer;
 import java.nio.CharBuffer;
 import java.sql.*;
 import java.text.SimpleDateFormat;
@@ -1454,7 +1455,7 @@ public class MonetPreparedStatement
 					e.getMessage(), "M1M25");
 		}
 		// We have to rewind the buffer, because otherwise toString() returns "".
-		buf.rewind();
+		((Buffer)buf).rewind();
 		setString(parameterIndex, buf.toString());
 	}
 

--- a/src/main/java/nl/cwi/monetdb/mcl/connection/mapi/AbstractSocket.java
+++ b/src/main/java/nl/cwi/monetdb/mcl/connection/mapi/AbstractSocket.java
@@ -158,7 +158,7 @@ public abstract class AbstractSocket imp
 		if(read == 0) {
 			throw new IOException("The server has reached EOF!");
 		}
-		this.stringsDecoded.clear();
+		((Buffer)this.stringsDecoded).clear();
 		this.utf8Decoder.reset();
 		this.utf8Decoder.decode(this.bufferIn, this.stringsDecoded,true);
 		this.utf8Decoder.flush(this.stringsDecoded);
@@ -173,7 +173,7 @@ public abstract class AbstractSocket imp
 	 * @throws IOException If an error in the underlying connection happened
 	 */
 	public CharBuffer readLine(CharBuffer lineBuffer) throws IOException {
-		lineBuffer.clear();
+		((Buffer)lineBuffer).clear();
 		boolean found = false;
 		char[] sourceArray = this.stringsDecoded.array();
 		int sourcePosition = this.stringsDecoded.position();
@@ -184,7 +184,7 @@ public abstract class AbstractSocket imp
 
 		while(!found) {
 			if(sourcePosition >= sourceLimit) {
-				this.stringsDecoded.position(sourcePosition);
+				((Buffer)this.stringsDecoded).position(sourcePosition);
 				this.readToInputBuffer();
 				sourceArray = this.stringsDecoded.array();
 				sourcePosition = 0;
@@ -202,8 +202,8 @@ public abstract class AbstractSocket imp
 				destinationArray[destinationPosition++] = c;
 			}
 		}
-		this.stringsDecoded.position(sourcePosition);
-		lineBuffer.position(destinationPosition);
+		((Buffer)this.stringsDecoded).position(sourcePosition);
+		((Buffer)lineBuffer).position(destinationPosition);
 		((Buffer)lineBuffer).flip();
 		return lineBuffer;
 	}
@@ -228,8 +228,8 @@ public abstract class AbstractSocket imp
 		this.utf8Encoder.flush(this.bufferOut);
 		written += this.writeFromBufferOut(this.bufferOut);
 
-		this.stringsEncoded.clear();
-		this.bufferOut.clear();
+		((Buffer)this.stringsEncoded).clear();
+		((Buffer)this.bufferOut).clear();
 		if(written == 0) {
 			throw new IOException("The query could not be sent to the server!");
 		} else {
@@ -253,14 +253,14 @@ public abstract class AbstractSocket imp
 
 		for (int i = 0; i < limit; i++) {
 			if (destinationPosition >= destinationCapacity) {
-				this.stringsEncoded.position(destinationPosition);
+				((Buffer)this.stringsEncoded).position(destinationPosition);
 				this.writeToOutputBuffer(false);
 				destinationArray = this.stringsEncoded.array();
 				destinationPosition = 0;
 			}
 			destinationArray[destinationPosition++] = line.charAt(i);
 		}
-		this.stringsEncoded.position(destinationPosition);
+		((Buffer)this.stringsEncoded).position(destinationPosition);
 	}
 
 	/**

--- a/src/main/java/nl/cwi/monetdb/mcl/connection/mapi/OldMapiSocket.java
+++ b/src/main/java/nl/cwi/monetdb/mcl/connection/mapi/OldMapiSocket.java
@@ -210,7 +210,7 @@ public class OldMapiSocket extends Abstr
 		}
 
 		public int read(ByteBuffer b, int off, int len) throws IOException {
-			b.clear();
+			((Buffer)b).clear();
 			int t;
 			int size = 0;
 			while (size < len) {
@@ -241,7 +241,7 @@ public class OldMapiSocket extends Abstr
 				throw new IOException("Read from " + connection.getHostname() + ":" +
 						connection.getPort() + ": Incomplete block read from stream");
 			}
-			b.position(size);
+			((Buffer)b).position(size);
 			((Buffer)b).flip();
 			return size;
 		}
@@ -350,7 +350,7 @@ public class OldMapiSocket extends Abstr
 					break;
 				}
 			}
-			b.clear();
+			((Buffer)b).clear();
 			return written;
 		}
 

--- a/src/main/java/nl/cwi/monetdb/mcl/protocol/oldmapi/OldMapiProtocol.java
+++ b/src/main/java/nl/cwi/monetdb/mcl/protocol/oldmapi/OldMapiProtocol.java
@@ -98,9 +98,9 @@ public class OldMapiProtocol extends Abs
 				throw new IOException("Connection to server lost!");
 			}
 			this.currentServerResponseHeader = OldMapiServerResponseParser.parseOldMapiServerResponse(this);
-			this.lineBuffer.position(0);
+			((Buffer)this.lineBuffer).position(0);
 			if (this.currentServerResponseHeader == ServerResponses.ERROR) {
-				this.lineBuffer.position(1);
+				((Buffer)this.lineBuffer).position(1);
 			}
 		}
 	}
@@ -130,7 +130,7 @@ public class OldMapiProtocol extends Abs
 			((Buffer)newbuffer).flip();
 			this.lineBuffer = newbuffer;
 		}
-		this.lineBuffer.position(1);
+		((Buffer)this.lineBuffer).position(1);
 	}
 
 	/**

--- a/src/main/java/nl/cwi/monetdb/mcl/protocol/oldmapi/OldMapiStartOfHeaderParser.java
+++ b/src/main/java/nl/cwi/monetdb/mcl/protocol/oldmapi/OldMapiStartOfHeaderParser.java
@@ -11,6 +11,8 @@ package nl.cwi.monetdb.mcl.protocol.oldm
 import nl.cwi.monetdb.mcl.protocol.ProtocolException;
 import nl.cwi.monetdb.mcl.protocol.StarterHeaders;
 
+import java.nio.Buffer;
+
 /**
  * The OldMapiStartOfHeaderParser is responsible to retrieve the server's headers on a SOHEADER response. Depending on
  * the type of the header, the next tokens should be retrieved as integers or Strings.
@@ -96,7 +98,7 @@ final class OldMapiStartOfHeaderParser {
 				throw new ProtocolException("expected a digit", currentPointer - 1);
 			}
 		}
-		protocol.lineBuffer.position(currentPointer);
+		((Buffer)protocol.lineBuffer).position(currentPointer);
 		return positive ? tmp : -tmp;
 	}
 
@@ -127,7 +129,7 @@ final class OldMapiStartOfHeaderParser {
 			cnt++;
 		}
 
-		protocol.lineBuffer.position(mark);
+		((Buffer)protocol.lineBuffer).position(mark);
 		return new String(array, 0, cnt);
 	}
 }

--- a/src/main/java/nl/cwi/monetdb/mcl/protocol/oldmapi/OldMapiTupleLineParser.java
+++ b/src/main/java/nl/cwi/monetdb/mcl/protocol/oldmapi/OldMapiTupleLineParser.java
@@ -103,7 +103,7 @@ final class OldMapiTupleLineParser {
 							final int fieldlen = endpos - cursor;
 							if (fieldHasEscape) {
 								// reuse the tupleLineBuffer by cleaning it and ensure the capacity
-								tupleLineBuffer.clear();
+								((Buffer)tupleLineBuffer).clear();
 								tupleLineBuffer = BufferReallocator.ensureCapacity(tupleLineBuffer, (i - 2) - (cursor + 1));
 								// parse the field value (excluding the double quotes) and convert it to a string without any escape characters
 								for (int pos = cursor; pos < endpos; pos++) {