diff --git a/lib/log.bash b/lib/log.bash
index 6bc53a12..f9769d60 100644
--- a/lib/log.bash
+++ b/lib/log.bash
@@ -1,4 +1,13 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+#
+# A collection of logging functions.
+
+# Avoid duplicate inclusion
+if [[ -n "${__bash_it_lib_log:-}" ]]
+then
+    return 0
+fi
+__bash_it_lib_log="loaded"
 
 export BASH_IT_LOG_LEVEL_ERROR=1
 export BASH_IT_LOG_LEVEL_WARNING=2
diff --git a/lib/utilities.bash b/lib/utilities.bash
index 575787d8..33e7aa8b 100644
--- a/lib/utilities.bash
+++ b/lib/utilities.bash
@@ -2,6 +2,13 @@
 #
 # A collection of reusable functions.
 
+# Avoid duplicate inclusion
+if [[ -n "${__bash_it_lib_utilities:-}" ]]
+then
+    return 0
+fi
+__bash_it_lib_utilities="loaded"
+
 ###########################################################################
 # Generic utilies
 ###########################################################################