diff --git a/outer_wrapper.py b/outer_wrapper.py
index bf704b6..84a43db 100755
--- a/outer_wrapper.py
+++ b/outer_wrapper.py
@@ -180,7 +180,7 @@ class OuterWrapper(ABC):
 
         self.input_schemas = None
         self.output_schemas = None
-        self.validated_schemas = {}
+        self.validated_messages = {"this_incstep": {}, "next_incstep": {}}
         self.generic_output_schema = (
             "{"
             '  "type": "object",'
@@ -389,18 +389,20 @@ class OuterWrapper(ABC):
         # validate against input schemas
         if (
             incstep > 1
-            and len(self.validated_schemas) != self.num_expected_inputs
+            and len(self.validated_messages["this_incstep"])
+            != self.num_expected_inputs
         ):
             logging.critical(
-                f"number of validated schemas {len(self.validated_schemas)} != num_expected_inputs {self.num_expected_inputs}"
+                f"number of validated messages {len(self.validated_messages['this_incstep'])} != num_expected_inputs {self.num_expected_inputs}"
             )
             event.set()
             raise RuntimeError
 
         # call the inner wrapper
-        schemas = self.validated_schemas.copy()
-        self.validated_schemas.clear()
-        results = self.increment(**schemas)
+        payloads = {}
+        for schema, message in self.validated_messages["this_incstep"].items():
+            payloads[schema] = message["payload"]
+        results = self.increment(**payloads)
 
         # validate against output schemas
         for schema_name, data_msg in results.items():
@@ -462,9 +464,21 @@ class OuterWrapper(ABC):
                         self.status = "ready"
 
                     elif (
-                        len(self.validated_schemas) == self.num_expected_inputs
+                        len(self.validated_messages["next_incstep"])
+                        == self.num_expected_inputs
                     ):
-                        # all input messages have been received and all input schemas have been validated
+                        # ready for an increment
+                        self.validated_messages[
+                            "this_incstep"
+                        ] = self.validated_messages["next_incstep"].copy()
+                        self.validated_messages["next_incstep"].clear()
+                        self.status = "ready"
+
+                    elif (
+                        len(self.validated_messages["this_incstep"])
+                        == self.num_expected_inputs
+                    ):
+                        # ready for an increment
                         self.status = "ready"
 
                     else:
@@ -634,10 +648,11 @@ class OuterWrapper(ABC):
                 logging.info(
                     f"schema {name} validated incoming message from {message['source']}"
                 )
-                if name in self.validated_schemas:
+                if name in self.validated_messages["next_incstep"]:
                     logging.error(
-                        f"schema {name} already validated a message: {message}"
+                        f"schema {name} already validated a message: {self.validated_messages['next_incstep'][name]}"
                     )
+                    logging.error(f"new message: {message}")
                     return False
                 else:
                     matched.append(schema)
@@ -681,7 +696,8 @@ class OuterWrapper(ABC):
                         ][item]["properties"]["data"].get("unit", "")
                         message["payload"][item]["granularity"] = dest_gran
 
-                    self.validated_schemas[name] = message["payload"]
+                    self.validated_messages["next_incstep"][name] = message
+
             except ValidationError:
                 logging.debug("validation error")
             except json.JSONDecodeError: