diff --git a/docs/manual/libudis86.rst b/docs/manual/libudis86.rst
index 67e1085..e8d42f5 100644
--- a/docs/manual/libudis86.rst
+++ b/docs/manual/libudis86.rst
@@ -492,10 +492,6 @@ Prefix bytes that affect the disassembly of the instruction are availabe in the
 following fields, each of which corressponds to a particular type or class of
 prefixes.
 
-.. c:member:: uint8_t ud_t.pfx_rex
-
-    64-bit mode REX prefix
-
 .. c:member:: uint8_t ud_t.pfx_rex
 
     64-bit mode REX prefix
@@ -516,6 +512,10 @@ prefixes.
 
     Lock prefix
 
+.. c:member:: uint8_t ud_t.pfx_str
+
+    String prefix
+
 .. c:member:: uint8_t ud_t.pfx_rep
 
     Rep prefix