diff --git a/src/histrefs.zsh b/src/histrefs.zsh
index 42346d1..3cd4fda 100644
--- a/src/histrefs.zsh
+++ b/src/histrefs.zsh
@@ -6,7 +6,11 @@
 # Prints to STDOUT the name of the histrefs file to use for current
 # working directory
 _zsh_prioritize_cwd_history_histrefs_for_cwd() {
-	local md5=$(echo "${PWD:A}" | md5 -q)
+	if ! type md5 > /dev/null;then
+		local md5=$(echo "${PWD:A}" | md5sum | cut -d' ' -f1)
+	else
+		local md5=$(echo "${PWD:A}" | md5 -q)
+	fi
 
 	echo "$ZSH_PRIORITIZE_CWD_HISTORY_DIR/.histrefs-$md5"
 }
@@ -49,7 +53,7 @@ _zsh_prioritize_cwd_history_load_cwd_history() {
 	# [ (valid_histrefs) ] || return
 
 	# Create a tmp file for use with `fc -R`
-	local template="$ZSH_PRIORITIZE_CWD_HISTORY_DIR/.tmphistXX"
+	local template="$ZSH_PRIORITIZE_CWD_HISTORY_DIR/.tmphistXXXX"
 	local tmp_histfile=$(mktemp "$template")
 
 	# Copy history entries executed in this directory to tmp file
diff --git a/zsh-prioritize-cwd-history.zsh b/zsh-prioritize-cwd-history.zsh
index 0fe6c1d..64fb207 100644
--- a/zsh-prioritize-cwd-history.zsh
+++ b/zsh-prioritize-cwd-history.zsh
@@ -50,7 +50,11 @@ ZSH_PRIORITIZE_CWD_HISTORY_DIR="$HOME/.zsh_prioritize_cwd_history"
 # Prints to STDOUT the name of the histrefs file to use for current
 # working directory
 _zsh_prioritize_cwd_history_histrefs_for_cwd() {
-	local md5=$(echo "${PWD:A}" | md5 -q)
+	if ! type md5 > /dev/null;then
+		local md5=$(echo "${PWD:A}" | md5sum | cut -d' ' -f1)
+	else
+		local md5=$(echo "${PWD:A}" | md5 -q)
+	fi
 
 	echo "$ZSH_PRIORITIZE_CWD_HISTORY_DIR/.histrefs-$md5"
 }
@@ -93,7 +97,7 @@ _zsh_prioritize_cwd_history_load_cwd_history() {
 	# [ (valid_histrefs) ] || return
 
 	# Create a tmp file for use with `fc -R`
-	local template="$ZSH_PRIORITIZE_CWD_HISTORY_DIR/.tmphistXX"
+	local template="$ZSH_PRIORITIZE_CWD_HISTORY_DIR/.tmphistXXXX"
 	local tmp_histfile=$(mktemp "$template")
 
 	# Copy history entries executed in this directory to tmp file