diff --git a/Jamfile.v2 b/Jamfile.v2
index 7cf95b9..b6ef149 100644
--- a/Jamfile.v2
+++ b/Jamfile.v2
@@ -14,8 +14,11 @@ import path ;
 import option ;
 
 local DIST_DIR = [ option.get distdir ] ;
-DIST_DIR ?= [ path.join $(BOOST_ROOT) dist ] ;
-DIST_DIR = [ path.root [ path.make $(DIST_DIR) ] [ path.pwd ] ] ;
+if $(DIST_DIR) {
+    DIST_DIR = [ path.root [ path.make $(DIST_DIR) ] [ path.pwd ] ] ;
+} else {
+    DIST_DIR = [ path.join $(BOOST_ROOT) dist ] ;
+}
 local DIST_BIN = [ path.join $(DIST_DIR) bin ] ;
 
 # Install quickbook by default.