diff --git a/lib/dbi/ogs-mongoc.c b/lib/dbi/ogs-mongoc.c
index c5dd87014..055eb5745 100644
--- a/lib/dbi/ogs-mongoc.c
+++ b/lib/dbi/ogs-mongoc.c
@@ -20,11 +20,9 @@
 #include <mongoc.h>
 
 #include "ogs-dbi.h"
-#include <string.h>
 
 int __ogs_dbi_domain;
 
-static char masked_db_uri[255];
 static ogs_mongoc_t self;
 
 /*
@@ -50,28 +48,32 @@ ogs_mongoc_mongoc_client_get_server_status (mongoc_client_t *client, /* IN */
    return ret;
 }
 
-const char* ogs_mask_db_uri(const char *db_uri)
+static char *masked_db_uri(const char *db_uri)
 {
-    bzero(masked_db_uri, sizeof(masked_db_uri));
-    if (strnlen(db_uri, sizeof(masked_db_uri)) == sizeof(masked_db_uri)) {
-        return db_uri;
-    }
+    char *tmp;
+    char *array[2], *saveptr = NULL;
+    char *masked = NULL;
 
-    char *token = strtok((char *)db_uri, "@");
-    if (strlen(token) > 1) {
-        strcpy((char *)masked_db_uri, "mongodb://*****:*****@");
-        while (token != NULL) {
-            token = strtok(NULL, "@");
-            if (token != NULL) {
-                strcat((char *)masked_db_uri, token);
-            }
-        }
+    ogs_assert(db_uri);
+
+    tmp = ogs_strdup(db_uri);
+
+    memset(array, 0, sizeof(array));
+    array[0] = strtok_r(tmp, "@", &saveptr);
+    if (array[0])
+        array[1] = strtok_r(NULL, "@", &saveptr);
+
+    if (array[1]) {
+        masked = ogs_msprintf("mongodb://*****:*****@%s", array[1]);
+        ogs_assert(masked);
     } else {
-        // no credentials provided, no need to mask anything
-        return db_uri;
+        masked = ogs_strdup(array[0]);
+        ogs_assert(masked);
     }
 
-    return masked_db_uri;
+    ogs_free(tmp);
+
+    return masked;
 }
 
 int ogs_mongoc_init(const char *db_uri)
@@ -89,13 +91,15 @@ int ogs_mongoc_init(const char *db_uri)
 
     memset(&self, 0, sizeof(ogs_mongoc_t));
 
+    self.masked_db_uri = masked_db_uri(db_uri);
+
     mongoc_init();
 
     self.initialized = true;
 
     self.client = mongoc_client_new(db_uri);
     if (!self.client) {
-        ogs_error("Failed to parse DB URI [%s]", ogs_mask_db_uri(db_uri));
+        ogs_error("Failed to parse DB URI [%s]", self.masked_db_uri);
         return OGS_ERROR;
     }
 
@@ -114,7 +118,7 @@ int ogs_mongoc_init(const char *db_uri)
 
     if (!ogs_mongoc_mongoc_client_get_server_status(
                 self.client, NULL, &reply, &error)) {
-        ogs_warn("Failed to connect to server [%s]", ogs_mask_db_uri(db_uri));
+        ogs_warn("Failed to connect to server [%s]", self.masked_db_uri);
         return OGS_RETRY;
     }
 
@@ -122,7 +126,7 @@ int ogs_mongoc_init(const char *db_uri)
 
     bson_destroy(&reply);
 
-    ogs_info("MongoDB URI: '%s'", ogs_mask_db_uri(db_uri));
+    ogs_info("MongoDB URI: '%s'", self.masked_db_uri);
 
     return OGS_OK;
 }
@@ -137,6 +141,10 @@ void ogs_mongoc_final(void)
         mongoc_client_destroy(self.client);
         self.client = NULL;
     }
+    if (self.masked_db_uri) {
+        ogs_free(self.masked_db_uri);
+        self.masked_db_uri = NULL;
+    }
 
     if (self.initialized) {
         mongoc_cleanup();
diff --git a/lib/dbi/ogs-mongoc.h b/lib/dbi/ogs-mongoc.h
index 8b2808324..9e3b4515b 100644
--- a/lib/dbi/ogs-mongoc.h
+++ b/lib/dbi/ogs-mongoc.h
@@ -37,12 +37,13 @@ typedef struct ogs_mongoc_s {
     void *client;
     void *database;
 
+    char *masked_db_uri;
+
     struct {
         void *subscriber;
     } collection;
 } ogs_mongoc_t;
 
-const char* ogs_mask_db_uri(const char *db_uri);
 int ogs_mongoc_init(const char *db_uri);
 void ogs_mongoc_final(void);
 ogs_mongoc_t *ogs_mongoc(void);