diff --git a/completion/available/terraform.completion.bash b/completion/available/terraform.completion.bash
index 9fe0795a..201b7267 100644
--- a/completion/available/terraform.completion.bash
+++ b/completion/available/terraform.completion.bash
@@ -28,21 +28,21 @@ _terraform()
 	if [[ ${cword} -eq 1 ]] ; then
 
 		# Options that do not start with a hyphen, are always starting with four spaces.
-		opts="$(terraform --help | grep -P '^\s\s\s\s\S' | awk '{print $1}')"
+		opts="$(terraform --help | grep -E '^\s\s\s\s\S' | awk '{print $1}')"
 		opts="${opts} --help --version"
 
 	elif [[ ${cword} -gt 1 ]] ; then
 
 		if [[ ${cword} -eq 2 && ${prev} == '--help' ]] ; then
 
-			opts="$(terraform --help | grep -P '^\s\s\s\s\S' | awk '{print $1}')"
+			opts="$(terraform --help | grep -E '^\s\s\s\s\S' | awk '{print $1}')"
 
 		elif [[ ${words[1]} != "--help" && ${words[1]} != "--version" && ${words[1]} != "version" ]] ; then
 
 			# Some commands accept hyphened parameters, ...
-			opts="$(terraform --help "${words[1]}" | grep -P '^\s+-' | awk '{print $1}' | awk -F '=' '{ if ($0 ~ /=/) {print $1"="} else {print $1} }')"
+			opts="$(terraform --help "${words[1]}" | grep -E '^\s+-' | awk '{print $1}' | awk -F '=' '{ if ($0 ~ /=/) {print $1"="} else {print $1} }')"
 			# but some other commands accept non-hyphened parameters.
-			opts="${opts} $(terraform --help "${words[1]}" | grep -P '^\s\s\s\s\S' | awk '{print $1}')"
+			opts="${opts} $(terraform --help "${words[1]}" | grep -E '^\s\s\s\s\S' | awk '{print $1}')"
 			# All of the commands accept the --help parameter which is not listed
 			# by the 'terraform --help <command>
 			opts="${opts} --help"