diff --git a/include/base/hex.hpp b/include/base/hex.hpp
index c6466f5..861e424 100644
--- a/include/base/hex.hpp
+++ b/include/base/hex.hpp
@@ -7,7 +7,7 @@
 
 namespace hex
 {
-    bool isValid(const char *str) noexcept;
+    bool isValid(const char *str, size_t str_size) noexcept;
     bool isValid(std::string_view str) noexcept;
 
     void encode(const uint8_t *data, size_t data_size, char *str, size_t str_size);
diff --git a/src/hex.cpp b/src/hex.cpp
index 5277954..4b1f9f8 100644
--- a/src/hex.cpp
+++ b/src/hex.cpp
@@ -27,9 +27,9 @@ static const int8_t hexmap[] = {
 
 namespace hex
 {
-    bool isValid(const char *str) noexcept
+    bool isValid(const char *str, size_t str_size) noexcept
     {
-        return baseN::isValid(str, hexmap);
+        return baseN::isValid(str, str_size, hexmap);
     }
     bool isValid(std::string_view str) noexcept
     {
diff --git a/test/test-hex.cpp b/test/test-hex.cpp
index 3a18aab..68542e1 100644
--- a/test/test-hex.cpp
+++ b/test/test-hex.cpp
@@ -17,9 +17,9 @@ TEST(hex, encode)
         EXPECT_STREQ(e.what(), "hex::encode: not enough allocated length");
     }
 }
-TEST(hex, encode_1e6)
+TEST(hex, encode_1e7)
 {
-    std::vector<uint8_t> data(1e6);
+    std::vector<uint8_t> data(1e7);
     encode(data);
 }
 TEST(hex, decode)
@@ -36,9 +36,9 @@ TEST(hex, decode)
         EXPECT_STREQ(e.what(), "hex::decode: isn't hex");
     }
 }
-TEST(hex, decode_1e6)
+TEST(hex, decode_1e7)
 {
-    std::string str(1e6, '0');
+    std::string str(1e7, '0');
     decode(str);
 }