diff --git a/CHANGELOG.md b/CHANGELOG.md
index ea464175..4dab7492 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@ This changelog documents the changes between release versions.
 
 ## [Unreleased]
 
+### Fixed
+
+- Escape field names or aliases with invalid characters in field selections ([#175](https://github.com/hasura/ndc-mongodb/pull/175))
+
 ## [1.8.3] - 2025-07-08
 
 ### Fixed
diff --git a/crates/integration-tests/src/tests/mod.rs b/crates/integration-tests/src/tests/mod.rs
index 1956d231..d1809e83 100644
--- a/crates/integration-tests/src/tests/mod.rs
+++ b/crates/integration-tests/src/tests/mod.rs
@@ -16,4 +16,5 @@ mod native_mutation;
 mod native_query;
 mod permissions;
 mod remote_relationship;
+mod selection;
 mod sorting;
diff --git a/crates/integration-tests/src/tests/selection.rs b/crates/integration-tests/src/tests/selection.rs
new file mode 100644
index 00000000..9f530322
--- /dev/null
+++ b/crates/integration-tests/src/tests/selection.rs
@@ -0,0 +1,20 @@
+use crate::{connector::Connector, run_connector_query};
+use insta::assert_yaml_snapshot;
+use ndc_test_helpers::{asc, field, query, query_request};
+
+#[tokio::test]
+async fn selects_fields_with_weird_aliases() -> anyhow::Result<()> {
+    assert_yaml_snapshot!(
+        run_connector_query(
+            Connector::SampleMflix,
+            query_request().collection("movies").query(
+                query()
+                    .fields([field!("foo.bar" => "title"), field!("year")])
+                    .limit(10)
+                    .order_by([asc!("_id")]),
+            )
+        )
+        .await?
+    );
+    Ok(())
+}
diff --git a/crates/integration-tests/src/tests/snapshots/integration_tests__tests__selection__selects_fields_with_weird_aliases.snap b/crates/integration-tests/src/tests/snapshots/integration_tests__tests__selection__selects_fields_with_weird_aliases.snap
new file mode 100644
index 00000000..e5d864bf
--- /dev/null
+++ b/crates/integration-tests/src/tests/snapshots/integration_tests__tests__selection__selects_fields_with_weird_aliases.snap
@@ -0,0 +1,25 @@
+---
+source: crates/integration-tests/src/tests/selection.rs
+expression: "run_connector_query(Connector::SampleMflix,\nquery_request().collection(\"movies\").query(query().fields([field!(\"foo.bar\" =>\n\"title\"), field!(\"year\")]).limit(10).order_by([asc!(\"_id\")]),)).await?"
+---
+- rows:
+    - foo.bar: Blacksmith Scene
+      year: 1893
+    - foo.bar: The Great Train Robbery
+      year: 1903
+    - foo.bar: The Land Beyond the Sunset
+      year: 1912
+    - foo.bar: A Corner in Wheat
+      year: 1909
+    - foo.bar: "Winsor McCay, the Famous Cartoonist of the N.Y. Herald and His Moving Comics"
+      year: 1911
+    - foo.bar: Traffic in Souls
+      year: 1913
+    - foo.bar: Gertie the Dinosaur
+      year: 1914
+    - foo.bar: In the Land of the Head Hunters
+      year: 1914
+    - foo.bar: The Perils of Pauline
+      year: 1914
+    - foo.bar: The Birth of a Nation
+      year: 1915
diff --git a/crates/mongodb-agent-common/src/mongodb/selection.rs b/crates/mongodb-agent-common/src/mongodb/selection.rs
index 614594c1..f60ef7dc 100644
--- a/crates/mongodb-agent-common/src/mongodb/selection.rs
+++ b/crates/mongodb-agent-common/src/mongodb/selection.rs
@@ -1,19 +1,18 @@
 use indexmap::IndexMap;
-use mongodb::bson::{doc, Bson, Document};
+use mongodb::bson::{bson, doc, Bson, Document};
 use mongodb_support::aggregate::Selection;
 use ndc_models::FieldName;
 
 use crate::{
     interface_types::MongoAgentError,
     mongo_query_plan::{Field, NestedArray, NestedField, NestedObject, QueryPlan},
-    mongodb::sanitize::get_field,
+    mongodb::sanitize::{get_field, is_name_safe},
     query::column_ref::ColumnRef,
 };
 
 pub fn selection_from_query_request(
     query_request: &QueryPlan,
 ) -> Result<Selection, MongoAgentError> {
-    // let fields = (&query_request.query.fields).flatten().unwrap_or_default();
     let empty_map = IndexMap::new();
     let fields = if let Some(fs) = &query_request.query.fields {
         fs
@@ -28,10 +27,11 @@ fn from_query_request_helper(
     parent: Option<ColumnRef<'_>>,
     field_selection: &IndexMap<ndc_models::FieldName, Field>,
 ) -> Result<Document, MongoAgentError> {
-    field_selection
+    let selection_doc = field_selection
         .iter()
         .map(|(key, value)| Ok((key.to_string(), selection_for_field(parent.clone(), value)?)))
-        .collect()
+        .collect::<Result<_, MongoAgentError>>()?;
+    Ok(escape_invalid_keys(selection_doc))
 }
 
 /// Wraps column reference with an `$isNull` check. That catches cases where a field is missing
@@ -175,6 +175,27 @@ fn nested_column_reference<'a>(
     }
 }
 
+/// If any key in our selection document contains invalid characters then we have to switch syntax
+/// to using $setField to escape the field name. Unfortunately this syntax is only capable of
+/// adding _one_ field to an object at a time, so we have to nest invocations of $setField for
+/// every selected field.
+fn escape_invalid_keys(doc: Document) -> Document {
+    if doc.keys().all(is_name_safe) {
+        return doc;
+    }
+    doc.into_iter()
+        .fold(None, |input: Option<Document>, (key, value)| {
+            Some(doc! {
+                "$setField": {
+                    "field": key,
+                    "value": value,
+                    "input": if let Some(prev_doc) = input { prev_doc.into() } else { bson!("$$CURRENT") },
+                }
+            })
+        })
+        .expect("selected at least one field") // safety: if the doc was empty we would have hit the early return
+}
+
 #[cfg(test)]
 mod tests {
     use configuration::Configuration;