diff --git a/configure.ac b/configure.ac
index b891ab7..829a8bf 100755
--- a/configure.ac
+++ b/configure.ac
@@ -1,7 +1,7 @@
 #############################################################################
 # Configuration for ctools - tools for science analysis of CTA data         #
 # ------------------------------------------------------------------------- #
-# Copyright (C) 2011-2020 Juergen Knoedlseder                               #
+# Copyright (C) 2011-2021 Juergen Knoedlseder                               #
 # ------------------------------------------------------------------------- #
 #                                                                           #
 #  This program is free software: you can redistribute it and/or modify     #
@@ -360,6 +360,13 @@ AC_SUBST(RUNSHARED)
 
 
 #############################################################################
+# Determine values of RTLD_GLOBAL and RTLD_NOW                              #
+#############################################################################
+AX_DLFLAGS(RTLD_GLOBAL)
+AX_DLFLAGS(RTLD_NOW)
+
+
+#############################################################################
 # Set -arch flags for universal builds on OSX and tweak BASECFLAGS based on #
 # compiler and platform (note that BASECFLAGS are not yet used).            #
 #############################################################################
diff --git a/m4/ax_dlflags.m4 b/m4/ax_dlflags.m4
new file mode 100644
index 0000000..c850fdb
--- /dev/null
+++ b/m4/ax_dlflags.m4
@@ -0,0 +1,52 @@
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_DLFLAGS
+#
+# DESCRIPTION
+#
+#   This macro determines the value of a DL flags such as RTLD_GLOBAL or
+#   RTLD_NOW from the dlfcn.h file.
+#
+# USAGE
+#
+#   AX_DLFLAGS(RTLD_GLOBAL)
+#   AC_MSG_RESULT($DLFLAGS_RTLD_GLOBAL)
+#
+# LICENSE
+#
+#   Copyright (c) 2021 Juergen Knoedlseder
+#
+#   This program is free software: you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#serial 8
+
+AC_DEFUN([AX_DLFLAGS], [
+  DLFLAGS_$1=""
+  AC_CHECK_HEADERS([dlfcn.h])
+  AS_IF([test "x$ac_cv_header_dlfcn_h" = "xyes"],[
+    AC_MSG_CHECKING([for value of $1])
+    for flags in 1 2 4 8 16 32 64 128 256 512 ; do
+      AC_EGREP_CPP([test_true],[
+        #include <dlfcn.h>
+        #if defined($1) && $1 == $flags
+        test_true
+        #endif
+        ],[DLFLAGS_$1=$flags],[])
+    done
+    ])
+  AC_MSG_RESULT($DLFLAGS_$1)
+  AC_SUBST([DLFLAGS_$1])
+])
diff --git a/pyext/ctools/__init__.py.in b/pyext/ctools/__init__.py.in
index e6c4661..9ece481 100755
--- a/pyext/ctools/__init__.py.in
+++ b/pyext/ctools/__init__.py.in
@@ -20,9 +20,18 @@
 # import gammalib first
 import gammalib
 
+# Make sur that library symbols are exported by setting the dynamic library
+# loading flag to RTLD_GLOBAL | RTLD_NOW. This is necessary on some systems.
+import sys
+flags = sys.getdlopenflags()
+sys.setdlopenflags(@DLFLAGS_RTLD_GLOBAL@ | @DLFLAGS_RTLD_NOW@)
+
 # Import sub modules
 from @PYTHON_RELATIVE_IMPORT@tools import *
 
+# Reset original flags
+sys.setdlopenflags(flags)
+
 # Remove swig register stuff
 bad_entries = [entry for entry in list(locals())
                if entry.endswith('_swigregister')]