diff --git a/lib/helpers.bash b/lib/helpers.bash
old mode 100755
new mode 100644
index f11df4be..59b5d58a
--- a/lib/helpers.bash
+++ b/lib/helpers.bash
@@ -1,4 +1,13 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+#
+# A collection of reusable functions.
+
+# Avoid duplicate inclusion
+if [[ -n "${__bash_it_lib_helpers:-}" ]]
+then
+    return 0
+fi
+__bash_it_lib_helpers="loaded"
 
 BASH_IT_LOAD_PRIORITY_DEFAULT_ALIAS=${BASH_IT_LOAD_PRIORITY_DEFAULT_ALIAS:-150}
 BASH_IT_LOAD_PRIORITY_DEFAULT_PLUGIN=${BASH_IT_LOAD_PRIORITY_DEFAULT_PLUGIN:-250}
diff --git a/lib/search.bash b/lib/search.bash
index 8bd95b8e..0d9f677b 100755
--- a/lib/search.bash
+++ b/lib/search.bash
@@ -1,6 +1,13 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
 #
 # Search by Konstantin Gredeskoul «github.com/kigster»
+
+# Avoid duplicate inclusion
+if [[ -n "${__bash_it_lib_search:-}" ]]
+then
+    return 0
+fi
+__bash_it_lib_search="loaded"
 #———————————————————————————————————————————————————————————————————————————————
 # This function returns list of aliases, plugins and completions in bash-it,
 # whose name or description matches one of the search terms provided as arguments.