diff --git a/modules/libpref/src/nsPref.cpp b/modules/libpref/src/nsPref.cpp
index 8fe416a1cbbf..d39a6cae0952 100644
--- a/modules/libpref/src/nsPref.cpp
+++ b/modules/libpref/src/nsPref.cpp
@@ -1305,6 +1305,7 @@ PR_IMPLEMENT(PrefResult) PREF_SavePrefFileSpecWith(
         }
     }
     PR_Free(valueArray);
+	fileSpec->closeStream();
     return PREF_NOERROR;
 }