diff --git a/net-http-server/src/main/java/org/xbib/net/http/server/session/memory/MemoryPropertiesSessionCodec.java b/net-http-server/src/main/java/org/xbib/net/http/server/session/memory/MemoryPropertiesSessionCodec.java
index 80d3a18..cef7b16 100644
--- a/net-http-server/src/main/java/org/xbib/net/http/server/session/memory/MemoryPropertiesSessionCodec.java
+++ b/net-http-server/src/main/java/org/xbib/net/http/server/session/memory/MemoryPropertiesSessionCodec.java
@@ -76,7 +76,12 @@ public class MemoryPropertiesSessionCodec implements Codec<Session> {
 
     private Properties toProperties(Map<String, Object> map) {
         Properties properties = new Properties();
-        properties.putAll(map);
+        map.forEach((k,v) -> {
+            // filter non-null keys and values for properties semantics
+            if (k != null && v != null) {
+                properties.put(k, v);
+            }
+        });
         return properties;
     }