diff --git a/CHANGELOG.md b/CHANGELOG.md
index c02e451f..98841a11 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ This changelog documents the changes between release versions.
 - Fix for databases with field names that begin with a dollar sign, or that contain dots ([#74](https://github.com/hasura/ndc-mongodb/pull/74))
 - Implement column-to-column comparisons within the same collection ([#74](https://github.com/hasura/ndc-mongodb/pull/74))
 - Fix error tracking collection with no documents by skipping such collections during CLI introspection ([#76](https://github.com/hasura/ndc-mongodb/pull/76))
+- If a field contains both `int` and `double` values then the field type is inferred as `double` instead of `ExtendedJSON` ([#77](https://github.com/hasura/ndc-mongodb/pull/77))
 
 ## [0.0.6] - 2024-05-01
 - Enables logging events from the MongoDB driver by setting the `RUST_LOG` variable ([#67](https://github.com/hasura/ndc-mongodb/pull/67))
diff --git a/crates/cli/src/introspection/type_unification.rs b/crates/cli/src/introspection/type_unification.rs
index 61a8a377..31e539e1 100644
--- a/crates/cli/src/introspection/type_unification.rs
+++ b/crates/cli/src/introspection/type_unification.rs
@@ -8,7 +8,10 @@ use configuration::{
 };
 use indexmap::IndexMap;
 use itertools::Itertools as _;
-use mongodb_support::{align::align, BsonScalarType::*};
+use mongodb_support::{
+    align::align,
+    BsonScalarType::{self, *},
+};
 use std::string::String;
 
 type ObjectField = WithName<schema::ObjectField>;
@@ -43,11 +46,13 @@ pub fn unify_type(type_a: Type, type_b: Type) -> Type {
         (Type::Scalar(Null), type_b) => type_b.make_nullable(),
         (type_a, Type::Scalar(Null)) => type_a.make_nullable(),
 
-        // Scalar types unify if they are the same type.
+        // Scalar types unify if they are the same type, or if one is a superset of the other.
         // If they are diffferent then the union is ExtendedJSON.
         (Type::Scalar(scalar_a), Type::Scalar(scalar_b)) => {
-            if scalar_a == scalar_b {
+            if scalar_a == scalar_b || is_supertype(&scalar_a, &scalar_b) {
                 Type::Scalar(scalar_a)
+            } else if is_supertype(&scalar_b, &scalar_a) {
+                Type::Scalar(scalar_b)
             } else {
                 Type::ExtendedJSON
             }
@@ -169,6 +174,10 @@ pub fn unify_object_types(
     merged_type_map.into_values().collect()
 }
 
+fn is_supertype(a: &BsonScalarType, b: &BsonScalarType) -> bool {
+    matches!((a, b), (Double, Int))
+}
+
 #[cfg(test)]
 mod tests {
     use std::collections::{HashMap, HashSet};
@@ -307,4 +316,34 @@ mod tests {
                 "Missing field in result type")
         }
     }
+
+    #[test]
+    fn test_double_and_int_unify_as_double() {
+        let double = || Type::Scalar(BsonScalarType::Double);
+        let int = || Type::Scalar(BsonScalarType::Int);
+
+        let u = unify_type(double(), int());
+        assert_eq!(u, double());
+
+        let u = unify_type(int(), double());
+        assert_eq!(u, double());
+    }
+
+    #[test]
+    fn test_nullable_double_and_int_unify_as_nullable_double() {
+        let double = || Type::Scalar(BsonScalarType::Double);
+        let int = || Type::Scalar(BsonScalarType::Int);
+
+        for (a, b) in [
+            (double().make_nullable(), int()),
+            (double(), int().make_nullable()),
+            (double().make_nullable(), int().make_nullable()),
+            (int(), double().make_nullable()),
+            (int().make_nullable(), double()),
+            (int().make_nullable(), double().make_nullable()),
+        ] {
+            let u = unify_type(a, b);
+            assert_eq!(u, double().make_nullable());
+        }
+    }
 }