diff --git a/src/utilities/replaceVariables.ts b/src/utilities/replaceVariables.ts
index e491416ed7..747931fab7 100644
--- a/src/utilities/replaceVariables.ts
+++ b/src/utilities/replaceVariables.ts
@@ -24,7 +24,7 @@ export function replaceVariables(
   return visit(valueNode, {
     Variable(node) {
       const varName = node.name.value;
-      const scopedVariableValues = fragmentVariableValues?.signatures[varName]
+      const scopedVariableValues = fragmentVariableValues?.sources[varName]
         ? fragmentVariableValues
         : variableValues;
 
@@ -32,29 +32,39 @@ export function replaceVariables(
         return { kind: Kind.NULL };
       }
 
-      if (scopedVariableValues.sources[varName] === undefined) {
-        const defaultValue =
-          scopedVariableValues.signatures[varName]?.defaultValue;
+      const scopedVariableSource = scopedVariableValues.sources[varName];
+      if (scopedVariableSource.value === undefined) {
+        const defaultValue = scopedVariableSource.signature.defaultValue;
         if (defaultValue !== undefined) {
           return defaultValue.literal;
         }
       }
 
       return valueToLiteral(
-        scopedVariableValues.sources[varName],
-        scopedVariableValues?.signature.type,
+        scopedVariableSource.value,
+        scopedVariableSource.signature.type,
       );
     },
     ObjectValue(node) {
       return {
         ...node,
         // Filter out any fields with a missing variable.
-        fields: node.fields.filter(
-          (field) =>
-            (field.value.kind !== Kind.VARIABLE ||
-              fragmentVariableValues?.sources[field.value.name.value]) ??
-            variableValues?.sources[field.value.name.value],
-        ),
+        fields: node.fields.filter((field) => {
+          if (field.value.kind !== Kind.VARIABLE) {
+            return true;
+          }
+          const scopedVariableSource =
+            fragmentVariableValues?.sources[field.value.name.value] ??
+            variableValues?.sources[field.value.name.value];
+
+          if (
+            scopedVariableSource?.value === undefined &&
+            scopedVariableSource?.signature.defaultValue === undefined
+          ) {
+            return false;
+          }
+          return true;
+        }),
       };
     },
   }) as ConstValueNode;