diff --git a/src/Makefile.am b/src/Makefile.am
index c2df7fa7b9..a4bcd230c2 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -2,6 +2,7 @@
 SUBDIRS = \
   doc \
   engine \
+  calculation \
   experimental \
   register \
   guile \
diff --git a/src/Makefile.in b/src/Makefile.in
index 2b2d89180f..b7d3aa17f3 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -115,7 +115,7 @@ USE_NLS = @USE_NLS@
 VERSION = @VERSION@
 l = @l@
 
-SUBDIRS =    doc   engine   experimental   register   guile   gnome   scm   quotes   pixmaps   optional
+SUBDIRS =    doc   engine   calculation   experimental   register   guile   gnome   scm   quotes   pixmaps   optional
 
 
 # Engine Makefile.am file.