diff --git a/DynamoDbEncryption/dafny/DynamoDbEncryption/src/DynamoToStruct.dfy b/DynamoDbEncryption/dafny/DynamoDbEncryption/src/DynamoToStruct.dfy
index a2dfff698..8af15b5b7 100644
--- a/DynamoDbEncryption/dafny/DynamoDbEncryption/src/DynamoToStruct.dfy
+++ b/DynamoDbEncryption/dafny/DynamoDbEncryption/src/DynamoToStruct.dfy
@@ -40,7 +40,7 @@ module DynamoToStruct {
   }
   by method {
     var attrNames : seq<AttributeName> := SortedSets.ComputeSetToSequence(item.Keys);
-    var m := new DafnyLibraries.MutableMap<AttributeName, StructuredDataTerminal>();
+    var m := new DafnyLibraries.MutableMap<AttributeName, StructuredDataTerminal>((k: AttributeName, v: StructuredDataTerminal) => true, false);
     SequenceIsSafeBecauseItIsInMemory(attrNames);
     for i : uint64 := 0 to |attrNames| as uint64 {
       var k := attrNames[i];
@@ -76,7 +76,7 @@ module DynamoToStruct {
   }
   by method {
     var attrNames : seq<AttributeName> := SortedSets.ComputeSetToSequence(orig.Keys);
-    var m := new DafnyLibraries.MutableMap<AttributeName, AttributeValue>();
+    var m := new DafnyLibraries.MutableMap<AttributeName, AttributeValue>((k: AttributeName, v: AttributeValue) => true, false);
     SequenceIsSafeBecauseItIsInMemory(attrNames);
     for i : uint64 := 0 to |attrNames| as uint64 {
       var k := attrNames[i];
@@ -125,7 +125,7 @@ module DynamoToStruct {
   }
   by method {
     var attrNames : seq<AttributeName> := SortedSets.ComputeSetToSequence(orig.Keys);
-    var m := new DafnyLibraries.MutableMap<AttributeName, AttributeValue>();
+    var m := new DafnyLibraries.MutableMap<AttributeName, AttributeValue>((k: AttributeName, v: AttributeValue) => true, false);
     SequenceIsSafeBecauseItIsInMemory(attrNames);
     for i : uint64 := 0 to |attrNames| as uint64 {
       var k := attrNames[i];
diff --git a/submodules/MaterialProviders b/submodules/MaterialProviders
index 952c42f1c..bb0ec0cb9 160000
--- a/submodules/MaterialProviders
+++ b/submodules/MaterialProviders
@@ -1 +1 @@
-Subproject commit 952c42f1c7cfad57cc9ea0115c2a0cb38164ead7
+Subproject commit bb0ec0cb959e6982cf2c154458c39865db083e84