diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..6b29d51
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,3 @@
+[build-system]
+# Minimum requirements for the build system to execute.
+requires = ["Cython>=0.29.34", "setuptools>=32.0.0"]
diff --git a/requirements.txt b/requirements.txt
index 16d2c18..fb2bbd6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,4 +2,4 @@ setuptools>=32.0.0
 Click>=7.0
 pytest==4.3.1
 tabulate==0.8.5
-Cython==0.29.14
\ No newline at end of file
+Cython>=0.29.34
diff --git a/youtokentome/cpp/utf8.h b/youtokentome/cpp/utf8.h
index 0888bb3..47f1049 100644
--- a/youtokentome/cpp/utf8.h
+++ b/youtokentome/cpp/utf8.h
@@ -3,6 +3,7 @@
 #include <vector>
 #include <string>
 #include <cassert>
+#include <cstdint>
 
 namespace vkcom {