diff --git a/src/hstr.c b/src/hstr.c
index ce3336d..ecc59ee 100644
--- a/src/hstr.c
+++ b/src/hstr.c
@@ -76,8 +76,8 @@
 #define HH_COLOR_DELETE  4
 #define HH_COLOR_MATCH   5
 
-#define HH_ENV_VAR_CONFIG    "HH_CONFIG"
-#define HH_ENV_VAR_PROMPT    "HH_PROMPT"
+#define HH_ENV_VAR_CONFIG      "HH_CONFIG"
+#define HH_ENV_VAR_PROMPT      "HH_PROMPT"
 
 #define HH_CONFIG_MONO       "monochromatic"
 #define HH_CONFIG_HICOLOR    "hicolor"
@@ -156,7 +156,7 @@ static const char *HH_CASE_LABELS[]={
         "sensitive"
 };
 
-static const char *INSTALL_STRING=
+static const char *INSTALL_BASH_STRING=
         "\n# add this configuration to ~/.bashrc"
         "\nexport HH_CONFIG=hicolor         # get more colors"
         "\nshopt -s histappend              # append new history items to .bash_history"
@@ -168,6 +168,12 @@ static const char *INSTALL_STRING=
         "\nif [[ $- =~ .*i.* ]]; then bind '\"\\C-r\": \"\\C-a hh \\C-j\"'; fi"
         "\n\n";
 
+static const char *INSTALL_ZSH_STRING=
+        "\n# add this configuration to ~/.zshrc"
+        "\nexport HISTFILE=~/.zsh_history   # ensure history file visibility"
+        "\nexport HH_CONFIG=hicolor         # get more colors"
+        "\n\n";
+
 static const char *HELP_STRING=
         "Usage: hh [option] [arg1] [arg2]..."
         "\nShell history suggest box:"
@@ -1117,7 +1123,12 @@ void hstr_getopt(int argc, char **argv, Hstr *hstr)
             printf("%s", HELP_STRING);
             exit(EXIT_SUCCESS);
         case 's':
-            printf("%s", INSTALL_STRING);
+            // ZSH_VERSION is not exported by Zsh > detected by parent process
+            if(isZshParentShell()) {
+                printf("%s", INSTALL_ZSH_STRING);
+            } else {
+                printf("%s", INSTALL_BASH_STRING);
+            }
             exit(EXIT_SUCCESS);
 
         case '?':
diff --git a/src/hstr_history.c b/src/hstr_history.c
index f54d245..47ad8d7 100644
--- a/src/hstr_history.c
+++ b/src/hstr_history.c
@@ -68,9 +68,9 @@ void dump_prioritized_history(HistoryItems *ph)
     printf("\n"); fflush(stdout);
 }
 
-int get_item_offset(char *historyFileName)
+int get_item_offset()
 {
-    if(strstr(historyFileName,"zsh")) {
+    if(isZshParentShell()) {
         // In zsh history file, the format of item is
         // [:][blank][unix_timestamp][:][0][;][cmd]
         // Such as:
@@ -94,7 +94,7 @@ HistoryItems *get_prioritized_history()
     }
     HISTORY_STATE *historyState=history_get_history_state();
 
-    int itemOffset = get_item_offset(historyFile);
+    int itemOffset = get_item_offset();
 
     if(historyState->length > 0) {
         HashSet rankmap;
diff --git a/src/hstr_utils.c b/src/hstr_utils.c
index cd02c4e..4c10f00 100644
--- a/src/hstr_utils.c
+++ b/src/hstr_utils.c
@@ -125,3 +125,29 @@ void toggle_case(char *str, bool lowercase) {
         }
     }
 }
+
+const char* get_process_name_by_pid(const int pid)
+{
+    char* name = (char*)calloc(256,sizeof(char));
+    if(name){
+        sprintf(name, "/proc/%d/cmdline",pid);
+        FILE* f = fopen(name,"r");
+        if(f){
+            size_t size = fread(name, sizeof(char), 256, f);
+            if(size>0){
+                if('\n'==name[size-1])
+                    name[size-1]='\0';
+            }
+            fclose(f);
+        }
+    }
+    return name;
+}
+
+bool isZshParentShell() {
+    pid_t parentPid=getppid();
+    const char* cmdline=get_process_name_by_pid(parentPid);
+    bool result=cmdline && strstr(cmdline, "zsh");
+    free(cmdline);
+    return result;
+}
diff --git a/src/include/hstr_utils.h b/src/include/hstr_utils.h
index 6315319..d2f3ce0 100644
--- a/src/include/hstr_utils.h
+++ b/src/include/hstr_utils.h
@@ -28,5 +28,6 @@ void fill_terminal_input(char* cmd, bool padding);
 void reverse_char_pointer_array(char **array, unsigned length);
 void get_hostname(int bufferSize, char *buffer);
 void toggle_case(char *str, bool lowercase);
+bool isZshParentShell();
 
 #endif