diff --git a/kwsys_ios_sstream.h.in b/kwsys_ios_sstream.h.in
index 8378cb368147e791c4ed952bd751a1b46de05864..0470ef3daf0f298d4d918bc2f508a4572189df37 100644
--- a/kwsys_ios_sstream.h.in
+++ b/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
 {