diff --git a/deploy/gppkg/gppkg_spec.yml.in b/deploy/gppkg/gppkg_spec.yml.in
index 474fda0..8be15b4 100644
--- a/deploy/gppkg/gppkg_spec.yml.in
+++ b/deploy/gppkg/gppkg_spec.yml.in
@@ -17,3 +17,6 @@
            echo 'For additional options run:';
            echo '$ madpack --help';
            echo 'Release notes and additional documentation can be found at http://madlib.apache.org';"
+PostUninstall:
+- Master: "rm $GPHOME/lib/postgresql/libmadlib.so"
+- Segment: "rm $GPHOME/lib/postgresql/libmadlib.so"
diff --git a/deploy/gppkg/madlib.spec.in b/deploy/gppkg/madlib.spec.in
index 78fdb90..c2ca316 100644
--- a/deploy/gppkg/madlib.spec.in
+++ b/deploy/gppkg/madlib.spec.in
@@ -54,6 +54,8 @@
 ln -nsf $RPM_INSTALL_PREFIX/madlib/Current/bin $RPM_INSTALL_PREFIX/madlib/bin
 ln -nsf $RPM_INSTALL_PREFIX/madlib/Current/doc $RPM_INSTALL_PREFIX/madlib/doc
 
+ln -nsf $RPM_INSTALL_PREFIX/madlib/Current/ports/greenplum/@GPDB_VERSION@/lib/libmadlib.so $RPM_INSTALL_PREFIX/lib/postgresql/libmadlib.so
+
 # creating symlink for madpack (does not work at present)
 # find $RPM_INSTALL_PREFIX/bin/madpack -type f -exec mv {} $RPM_INSTALL_PREFIX/bin/old_madpack \; 2>/dev/null
 # ln -nsf $RPM_INSTALL_PREFIX/madlib/Current/bin/madpack $RPM_INSTALL_PREFIX/bin/madpack
diff --git a/src/madpack/changelist_1.18.0_1.19.0-dev.yaml b/src/madpack/changelist_1.18.0_1.19.0-dev.yaml
new file mode 100644
index 0000000..c1aad8d
--- /dev/null
+++ b/src/madpack/changelist_1.18.0_1.19.0-dev.yaml
@@ -0,0 +1,50 @@
+# ------------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ------------------------------------------------------------------------------
+
+# Changelist for MADlib version rel/v1.15 to rel/v1.15.1
+
+# This file contains all changes that were introduced in a new version of
+# MADlib. This changelist is used by the upgrade script to detect what objects
+# should be upgraded (while retaining all other objects from the previous version)
+
+# New modules (actually .sql_in files) added in upgrade version
+# For these files the sql_in code is retained as is with the functions in the
+# file installed on the upgrade version. All other files (that don't have
+# updates), are cleaned up to remove object replacements
+new module:
+
+# Changes in the types (UDT) including removal and modification
+udt:
+
+# List of the UDF changes that affect the user externally. This includes change
+# in function name, return type, argument order or types, or removal of
+# the function. In each case, the original function is as good as removed and a
+# new function is created. In such cases, we should abort the upgrade if there
+# are user views dependent on this function, since the original function will
+# not be present in the upgraded version.
+udf:
+
+# Changes to aggregates (UDA) including removal and modification
+# Overloaded functions should be mentioned separately
+uda:
+
+# List of the UDC, UDO and UDOC changes.
+udc:
+udo:
+udoc:
diff --git a/src/madpack/madpack.py b/src/madpack/madpack.py
index f620a68..e29e0cf 100755
--- a/src/madpack/madpack.py
+++ b/src/madpack/madpack.py
@@ -1232,6 +1232,13 @@
     for idx in range(len(madlib_functions)):
 
         func = madlib_functions[idx]
+
+        # Filter out the DEFAULT value from the function arguments
+        # DROP FUNCTION statements do not need or allow default values:
+        # DROP FUNCTION foo(bar INTEGER DEFAULT 0);
+        func['args'] = func['args'].split(',')
+        func['args'] = [i.split('DEFAULT')[0] for i in func['args']]
+        func['args'] = ', '.join(func['args'])
         # We don't drop type related functions
         no_drop = ['bytea8', 'float8arr', 'svec']
         if not any(x in func['name'] for x in no_drop):
@@ -1403,7 +1410,10 @@
             maddir_conf = maddir + "/config"
 
         global maddir_lib
-        if os.path.isfile(maddir + "/ports/" + portid + "/" + dbver +
+        if portid == 'greenplum' and \
+           os.path.islink(maddir + "/../../../lib/postgresql/libmadlib.so"):
+           maddir_lib = '$libdir/libmadlib.so'
+        elif os.path.isfile(maddir + "/ports/" + portid + "/" + dbver +
                           "/lib/libmadlib.so"):
             maddir_lib = maddir + "/ports/" + portid + "/" + dbver + \
                 "/lib/libmadlib.so"