diff --git a/Source/kwsys/kwsys_ios_sstream.h.in b/Source/kwsys/kwsys_ios_sstream.h.in
index e4aad8cfd..727a7891a 100644
--- a/Source/kwsys/kwsys_ios_sstream.h.in
+++ b/Source/kwsys/kwsys_ios_sstream.h.in
@@ -50,6 +50,7 @@
 // ostringstream and istringstream classes.
 
 # include <@KWSYS_NAMESPACE@/stl/string>
+# include <new> // Need placement operator new.
 
 namespace @KWSYS_NAMESPACE@_ios
 {