diff --git a/src/paramdict.cpp b/src/paramdict.cpp
index a6a7c893c2e..4704ea169e6 100644
--- a/src/paramdict.cpp
+++ b/src/paramdict.cpp
@@ -372,14 +372,6 @@ int ParamDict::load_param(const DataReader& dr)
                 d->params[id].s = std::string(vstr);
             }
 
-#if NCNN_SIMPLESTL
-            // simple stl string has no tail zero by default, append one
-            int len = d->params[id].s.size();
-            d->params[id].s.resize(len + 1);
-            d->params[id].s[len] = '\0';
-            d->params[id].s.resize(len);
-#endif
-
             d->params[id].type = 7;
 
             continue;
@@ -565,13 +557,6 @@ int ParamDict::load_param_bin(const DataReader& dr)
 
             d->params[id].s = tmpstr.data();
 
-#if NCNN_SIMPLESTL
-            // simple stl string has no tail zero by default, append one
-            d->params[id].s.resize(len + 1);
-            d->params[id].s[len] = '\0';
-            d->params[id].s.resize(len);
-#endif
-
             d->params[id].type = 7;
         }
         else if (is_array)
diff --git a/src/simplestl.h b/src/simplestl.h
index 00ff4680186..992bf9bcc4a 100644
--- a/src/simplestl.h
+++ b/src/simplestl.h
@@ -536,15 +536,11 @@ struct NCNN_EXPORT string : public vector<char>
     }
     bool operator==(const string& str2) const
     {
-        return strcmp(data_, str2.data_) == 0;
+        return size_ == str2.size_ && strncmp(data_, str2.data_, size_) == 0;
     }
-    bool operator==(const char* str2) const
+    bool operator!=(const string& str2) const
     {
-        return strcmp(data_, str2) == 0;
-    }
-    bool operator!=(const char* str2) const
-    {
-        return strcmp(data_, str2) != 0;
+        return size_ != str2.size_ || strncmp(data_, str2.data_, size_) != 0;
     }
     string& operator+=(const string& str1)
     {