diff --git a/Cargo.toml b/Cargo.toml
index d286a14d..fdcf6a57 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,7 +12,7 @@ actix-http = "=3.0.0-beta.14"
 actix-web = "=4.0.0-beta.13"
 async-trait = "0.1"
 bs58 = "0.4"
-cost-model = {git = "ssh://git@github.com/graphprotocol/agora.git", rev = "48bf329"}
+cost-model = {git = "ssh://git@github.com/graphprotocol/agora.git", rev = "c7c9876"}
 eventuals = "0.6"
 futures = "0.3"
 futures-util = "0.3"
diff --git a/src/query_engine/mod.rs b/src/query_engine/mod.rs
index 175a738b..f6fe51b0 100644
--- a/src/query_engine/mod.rs
+++ b/src/query_engine/mod.rs
@@ -297,6 +297,24 @@ impl<I: IndexerInterface + Clone + Send + 'static> QueryEngine<I> {
                 &[&deployment_ipfs],
                 |hist| hist.start_timer(),
             );
+
+            // Since we modify the context in-place, we need to reset the context to the state of
+            // the original client query. This to avoid the following scenario:
+            // 1. A client query has no block requirements set for some top-level operation
+            // 2. The first indexer is selected, with some indexing status at block number `n`
+            // 3. The query is made deterministic by setting the block requirement to the hash of
+            //    block `n`
+            // 4. Some condition requires us to retry this query on another indexer with an indexing
+            //    status at a block less than `n`
+            // 5. The same context is re-used, including the block requirement set to the hash of
+            //    block `n`
+            // 6. The indexer is seen as being behind and is unnecessarily penalized
+            //
+            // TODO: Avoid the additional cloning of the entire AST here, especially in the case
+            // where retries are necessary. Only the top-level operation arguments need to be reset
+            // to the state of the client query.
+            let mut context = context.clone();
+
             let selection_result = self
                 .indexers
                 .select_indexer(
diff --git a/src/query_engine/tests.rs b/src/query_engine/tests.rs
index 7324ac26..59dc3798 100644
--- a/src/query_engine/tests.rs
+++ b/src/query_engine/tests.rs
@@ -565,7 +565,9 @@ impl IndexerInterface for TopologyIndexer {
             let hash = capture.get(1).unwrap().as_str().parse::<Bytes32>().unwrap();
             let number = blocks.iter().position(|block| block.hash == hash).unwrap();
             if number > indexer.block(blocks.len()) {
-                todo!("block ahead of indexer")
+                return Err(
+                    "Failed to decode `block.hash` value: `no block with that hash found`".into(),
+                );
             }
         }
         Ok(IndexerResponse {