#5618: fix typo.
diff --git a/Doc/c-api/structures.rst b/Doc/c-api/structures.rst
index e92827d..c79c4cb 100644
--- a/Doc/c-api/structures.rst
+++ b/Doc/c-api/structures.rst
@@ -247,7 +247,7 @@
    T_OBJECT_EX     PyObject \*
    T_CHAR          char
    T_BYTE          char
-   T_UNBYTE        unsigned char
+   T_UBYTE         unsigned char
    T_UINT          unsigned int
    T_USHORT        unsigned short
    T_ULONG         unsigned long