diff --git a/src/lib/util/tests/Makefile.am b/src/lib/util/tests/Makefile.am
index 98d90d013a..dc144bdccd 100644
--- a/src/lib/util/tests/Makefile.am
+++ b/src/lib/util/tests/Makefile.am
@@ -3,6 +3,10 @@ SUBDIRS = .
 AM_CPPFLAGS = -I$(top_builddir)/src/lib -I$(top_srcdir)/src/lib
 AM_CPPFLAGS += $(BOOST_INCLUDES)
 AM_CPPFLAGS += -DTEST_DATA_BUILDDIR=\"$(abs_builddir)\"
+# XXX: we'll pollute the top builddir for creating a temporary test file
+# used to bind a UNIX domain socket so we can minimize the risk of exceeding
+# the limit of file name path size.
+AM_CPPFLAGS += -DTEST_DATA_TOPBUILDDIR=\"$(abs_top_builddir)\"
 AM_CXXFLAGS = $(B10_CXXFLAGS)
 
 if USE_STATIC_LINK
diff --git a/src/lib/util/tests/socketsession_unittest.cc b/src/lib/util/tests/socketsession_unittest.cc
index eade68a733..d736014362 100644
--- a/src/lib/util/tests/socketsession_unittest.cc
+++ b/src/lib/util/tests/socketsession_unittest.cc
@@ -50,7 +50,7 @@ using namespace isc::util::io::internal;
 
 namespace {
 
-const char* const TEST_UNIX_FILE = TEST_DATA_BUILDDIR "/test.unix";
+const char* const TEST_UNIX_FILE = TEST_DATA_TOPBUILDDIR "/test.unix";
 const char* const TEST_PORT = "53535";
 const char TEST_DATA[] = "BIND10 test";