add missing dependency
diff --git a/Doc/Makefile.deps b/Doc/Makefile.deps
index 3d38a74..5ac902b 100644
--- a/Doc/Makefile.deps
+++ b/Doc/Makefile.deps
@@ -141,6 +141,7 @@
 	lib/libmath.tex \
 	lib/librand.tex \
 	lib/libwhrandom.tex \
+	lib/libdecimal.tex \
 	lib/libarray.tex \
 	lib/liballos.tex \
 	lib/libos.tex \