diff --git a/lib/sandbox.js b/lib/sandbox.js
index d661c49..560f596 100644
--- a/lib/sandbox.js
+++ b/lib/sandbox.js
@@ -98,13 +98,13 @@ class ParameterWrapper {
 
         if (state.revision !== unpackedRevision) {
           unpackedRevision = state.revision;
-          unpacked = device.unpack(state.sessionContext.deviceData, path, state.revision + 1);
+          unpacked = device.unpack(state.sessionContext.deviceData, path, state.revision);
         }
 
         if (!unpacked.length)
           return undefined;
 
-        let attr = state.sessionContext.deviceData.attributes.get(unpacked[0], state.revision + 1)[attrName];
+        let attr = state.sessionContext.deviceData.attributes.get(unpacked[0], state.revision)[attrName];
 
         if (!attr)
           return undefined;
@@ -119,7 +119,7 @@ class ParameterWrapper {
 
       if (state.revision !== unpackedRevision) {
         unpackedRevision = state.revision;
-        unpacked = device.unpack(state.sessionContext.deviceData, path, state.revision + 1);
+        unpacked = device.unpack(state.sessionContext.deviceData, path, state.revision);
       }
 
       if (!unpacked.length)
@@ -134,7 +134,7 @@ class ParameterWrapper {
 
       if (state.revision !== unpackedRevision) {
         unpackedRevision = state.revision;
-        unpacked = device.unpack(state.sessionContext.deviceData, path, state.revision + 1);
+        unpacked = device.unpack(state.sessionContext.deviceData, path, state.revision);
       }
 
       if (!unpacked.length)
@@ -149,7 +149,7 @@ class ParameterWrapper {
 
       if (state.revision !== unpackedRevision) {
         unpackedRevision = state.revision;
-        unpacked = device.unpack(state.sessionContext.deviceData, path, state.revision + 1);
+        unpacked = device.unpack(state.sessionContext.deviceData, path, state.revision);
       }
 
       for (let p of unpacked)