diff --git a/src/common/cpp_essentials/decoder_result.rs b/src/common/cpp_essentials/decoder_result.rs
index bccd94a..0897d76 100644
--- a/src/common/cpp_essentials/decoder_result.rs
+++ b/src/common/cpp_essentials/decoder_result.rs
@@ -51,6 +51,9 @@ where
     pub fn with_eci_string_builder(src: ECIStringBuilder) -> Self {
         let mut new_self = Self::default();
         new_self.content = src;
+
+        
+
         new_self
     }
 
diff --git a/src/common/eci.rs b/src/common/eci.rs
index 3d8e6ce..699a529 100644
--- a/src/common/eci.rs
+++ b/src/common/eci.rs
@@ -6,7 +6,7 @@ use super::CharacterSet;
 
 use crate::common::Result;
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum Eci {
     Unknown = -1,
     Cp437 = 2, // obsolete
diff --git a/src/common/eci_string_builder.rs b/src/common/eci_string_builder.rs
index 0d0e63f..c5166bb 100644
--- a/src/common/eci_string_builder.rs
+++ b/src/common/eci_string_builder.rs
@@ -22,11 +22,11 @@
 // import java.nio.charset.StandardCharsets;
 
 use std::{
-    collections::HashMap,
+    collections::{HashMap, HashSet},
     fmt::{self, Display},
 };
 
-use crate::BarcodeFormat;
+use crate::{pdf417::decoder::ec, BarcodeFormat};
 
 use super::{CharacterSet, Eci, StringUtils};
 
@@ -125,6 +125,12 @@ impl ECIStringBuilder {
             }
 
             self.eci_positions.push((eci, self.bytes.len(), 0));
+
+            let ecis = self.list_ecis();
+
+            if ecis.len() <= 1 && (ecis.contains(&Eci::Unknown)) {
+                self.has_eci = false;
+            }
         }
     }
 
@@ -263,6 +269,14 @@ impl ECIStringBuilder {
 
         self
     }
+
+    pub fn list_ecis(&self) -> HashSet<Eci> {
+        let mut hs = HashSet::new();
+        self.eci_positions.iter().for_each(|pos| {
+            hs.insert(pos.0);
+        });
+        hs
+    }
 }
 
 impl fmt::Display for ECIStringBuilder {