diff --git a/.changeset/pretty-lobsters-push.md b/.changeset/pretty-lobsters-push.md
new file mode 100644
index 0000000000..7cca14b936
--- /dev/null
+++ b/.changeset/pretty-lobsters-push.md
@@ -0,0 +1,5 @@
+---
+'houdini-svelte': patch
+---
+
+Invalid integer route paramters get unmarshaled as undefined
diff --git a/packages/houdini/src/runtime/lib/scalars.test.ts b/packages/houdini/src/runtime/lib/scalars.test.ts
index a4d5a215a2..cd6c4ad5f3 100644
--- a/packages/houdini/src/runtime/lib/scalars.test.ts
+++ b/packages/houdini/src/runtime/lib/scalars.test.ts
@@ -956,6 +956,18 @@ describe('parseScalar', function () {
 			value: '1',
 			expected: 1,
 		},
+		{
+			title: 'invalid Int',
+			type: 'Int',
+			value: '',
+			expected: undefined,
+		},
+		{
+			title: 'invalid Float',
+			type: 'Float',
+			value: '',
+			expected: undefined,
+		},
 		{
 			title: 'Boolean',
 			type: 'Boolean',
diff --git a/packages/houdini/src/runtime/lib/scalars.ts b/packages/houdini/src/runtime/lib/scalars.ts
index dbd25c77c9..a383726730 100644
--- a/packages/houdini/src/runtime/lib/scalars.ts
+++ b/packages/houdini/src/runtime/lib/scalars.ts
@@ -199,8 +199,12 @@ export function isScalar(config: ConfigFile, type: string) {
 export function parseScalar(
 	config: ConfigFile,
 	type: string,
-	value: string
-): string | number | boolean {
+	value?: string
+): string | number | boolean | undefined {
+	if (typeof value === 'undefined') {
+		return undefined
+	}
+
 	if (type === 'Boolean') {
 		return value === 'true'
 	}
@@ -211,10 +215,18 @@ export function parseScalar(
 		return value
 	}
 	if (type === 'Int') {
-		return parseInt(value, 10)
+		const result = parseInt(value, 10)
+		if (Number.isNaN(result)) {
+			return undefined
+		}
+		return result
 	}
 	if (type === 'Float') {
-		return parseFloat(value)
+		const result = parseFloat(value)
+		if (Number.isNaN(result)) {
+			return undefined
+		}
+		return result
 	}
 
 	// if we have a special parse function, use it