diff --git a/doc/Guidebook.mn b/doc/Guidebook.mn
index b32144a6d..60a993cd5 100644
--- a/doc/Guidebook.mn
+++ b/doc/Guidebook.mn
@@ -6820,7 +6820,7 @@ been released as version 4.0.
 NetHack 5.0.0 was released on May 2, 2026.
 .pg
 The source code for NetHack 5.0.0 was modified and modernized to be
-compliant with standard C99. The 5.0.0 release contained over 3100 fixes,
+compliant with the C99 standard. The 5.0.0 release contained over 3100 fixes,
 changes, and updated features.
 .pg
 NetHack 5.0 was the first version to replace the lex and yacc level
diff --git a/doc/Guidebook.tex b/doc/Guidebook.tex
index 20bd1fcaa..e0c1e43c5 100644
--- a/doc/Guidebook.tex
+++ b/doc/Guidebook.tex
@@ -7578,7 +7578,7 @@ been released as version 4.0.
 %.pg
 \medskip
 The source code for \textit{NetHack} 5.0.0 was modified and modernized to be
-compliant with standard C99. The 5.0.0 release contained over 3100 fixes,
+compliant with the C99 standard. The 5.0.0 release contained over 3100 fixes,
 changes, and updated features.
 
 %.pg