diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6864d16be..2ef4424c2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -38,6 +38,10 @@ option(BUILD_SHARED_LIBS "Build using shared libraries" OFF)
 if(NOT BUILD_STATIC_LIBS AND NOT BUILD_SHARED_LIBS)
    message(FATAL_ERROR "At least one of BUILD_SHARED_LIBS or BUILD_STATIC_LIBS must be ON.")
 endif()
+option(USE_64BIT_INTEGERS "Use 64-bit integers" OFF)
+if(USE_64BIT_INTEGERS)
+   add_compile_definitions(USE_64BIT_INTEGERS)
+endif()
 
 # determine whether a Fortran compiler is required, based on the available optional dependencies
 find_library(HSL hsl)
diff --git a/uno/integer_type/integer_type.hpp b/uno/integer_type/integer_type.hpp
new file mode 100644
index 000000000..841dd8a98
--- /dev/null
+++ b/uno/integer_type/integer_type.hpp
@@ -0,0 +1,15 @@
+// Copyright (c) 2025 Charlie Vanaret
+// Licensed under the MIT license. See LICENSE file in the project directory for details.
+
+#ifndef UNO_INTEGERTYPE_H
+#define UNO_INTEGERTYPE_H
+
+#include <cstdint>
+
+#ifdef USE_64BIT_INTEGERS
+using UnoInt = int64_t;
+#else
+using UnoInt = int32_t;
+#endif
+
+#endif // UNO_INTEGERTYPE_H
\ No newline at end of file