diff --git config/stl-headers config/stl-headers
index c057d8e..dc7f6f0 100644
--- mozilla/config/stl-headers
+++ mozilla/config/stl-headers
@@ -21,6 +21,7 @@ algorithm
 atomic
 deque
 ios
+iosfwd
 iostream
 iterator
 limits
diff --git config/system-headers config/system-headers
index d31c94e..570c82a 100644
--- mozilla/config/system-headers
+++ mozilla/config/system-headers
@@ -469,6 +469,7 @@ IOKit/IOMessage.h
 IOKit/pwr_mgt/IOPMLib.h
 iomanip
 ios
+iosfwd
 iostream
 iostream.h
 iterator
diff --git js/src/config/system-headers js/src/config/system-headers
index d31c94e..570c82a 100644
--- mozilla/js/src/config/system-headers
+++ mozilla/js/src/config/system-headers
@@ -469,6 +469,7 @@ IOKit/IOMessage.h
 IOKit/pwr_mgt/IOPMLib.h
 iomanip
 ios
+iosfwd
 iostream
 iostream.h
 iterator