diff --git a/backend/gs1.c b/backend/gs1.c
index b477751b..39791f8e 100644
--- a/backend/gs1.c
+++ b/backend/gs1.c
@@ -494,7 +494,7 @@ INTERNAL int gs1_verify(struct zint_symbol *symbol, const unsigned char source[]
         }
         
         if (ai_value[i] == 253) { // GDTI
-            if ((data_length[i] < 14) || (data_length[i] > 30)) {
+            if ((data_length[i] < 13) || (data_length[i] > 30)) {
                 error_latch = 1;
             } else {
                 error_latch = 0;
@@ -502,7 +502,7 @@ INTERNAL int gs1_verify(struct zint_symbol *symbol, const unsigned char source[]
         }
         
         if (ai_value[i] == 255) { // GCN
-            if ((data_length[i] < 14) || (data_length[i] > 25)) {
+            if ((data_length[i] < 13) || (data_length[i] > 25)) {
                 error_latch = 1;
             } else {
                 error_latch = 0;
diff --git a/backend/tests/test_gs1.c b/backend/tests/test_gs1.c
index ee1b3b7c..ecdcb488 100644
--- a/backend/tests/test_gs1.c
+++ b/backend/tests/test_gs1.c
@@ -349,10 +349,14 @@ static void test_gs1_verify(int index) {
         /* 64*/ { "[251]abcdefghijklmnopqrstuvwxyz1234", 0, "251abcdefghijklmnopqrstuvwxyz1234" },
         /* 65*/ { "[251]abcdefghijklmnopqrstuvwxyz12345", ZINT_ERROR_INVALID_DATA, "" },
         /* 66*/ { "[252]1234", ZINT_ERROR_INVALID_DATA, "" },
+        /* 67*/ { "[253]131313131313", ZINT_ERROR_INVALID_DATA, "" },
+        /* 67*/ { "[253]1313131313134", 0, "2531313131313134" },
         /* 67*/ { "[253]131313131313412345678901234567", 0, "253131313131313412345678901234567" },
-        /* 68*/ { "[253]13131313131341234567890123345678", ZINT_ERROR_INVALID_DATA, "" },
+        /* 68*/ { "[253]1313131313134123456789012345678", ZINT_ERROR_INVALID_DATA, "" },
         /* 69*/ { "[254]abcdefghijklmnopqrst", 0, "254abcdefghijklmnopqrst" },
         /* 70*/ { "[254]abcdefghijklmnopqrstu", ZINT_ERROR_INVALID_DATA, "" },
+        /* 71*/ { "[255]131313131313", ZINT_ERROR_INVALID_DATA, "" },
+        /* 71*/ { "[255]1313131313134", 0, "2551313131313134" },
         /* 71*/ { "[255]1313131313134123456789012", 0, "2551313131313134123456789012" },
         /* 72*/ { "[255]13131313131341234567890123", ZINT_ERROR_INVALID_DATA, "" },
         /* 73*/ { "[256]1234", ZINT_ERROR_INVALID_DATA, "" },