"\platform{UNIX}" should really be spelled "\platform{Unix}".
diff --git a/Doc/lib/libgdbm.tex b/Doc/lib/libgdbm.tex
index 585693c..73683ca 100644
--- a/Doc/lib/libgdbm.tex
+++ b/Doc/lib/libgdbm.tex
@@ -2,7 +2,7 @@
          GNU's reinterpretation of dbm}
 
 \declaremodule{builtin}{gdbm}
-  \platform{UNIX}
+  \platform{Unix}
 \modulesynopsis{GNU's reinterpretation of dbm.}