--- file_not_specified_in_diff	
+++ file_not_specified_in_diff	
@@ -23,1 +23,1 @@ 
-IUSE="debug kerberos mms-agent ssl static-libs"
---
+IUSE="debug kerberos mms-agent ssl static-libs +system-boost"
@@ -48,1 +48,0 @@ 
-	scons_opts+=" --use-system-boost"
@@ -55,0 +54,4 @@ 
+
+    if use system-boost; then
+		scons_opts+=" --use-system-boost"
+	fi