diff --git a/src/transformation/utils/function-context.ts b/src/transformation/utils/function-context.ts
index 41e70d40f..154150bd1 100644
--- a/src/transformation/utils/function-context.ts
+++ b/src/transformation/utils/function-context.ts
@@ -116,7 +116,15 @@ function reduceContextTypes(contexts: ContextType[]): ContextType {
 }
 
 function getSignatureDeclarations(context: TransformationContext, signature: ts.Signature): ts.SignatureDeclaration[] {
+    if (signature.compositeSignatures) {
+        return signature.compositeSignatures.flatMap(s => getSignatureDeclarations(context, s));
+    }
+
     const signatureDeclaration = signature.getDeclaration();
+    if (signatureDeclaration === undefined) {
+        return [];
+    }
+
     let inferredType: ts.Type | undefined;
     if (
         ts.isMethodDeclaration(signatureDeclaration) &&
diff --git a/src/typescript-internal.d.ts b/src/typescript-internal.d.ts
index afcf45685..59995ebce 100644
--- a/src/typescript-internal.d.ts
+++ b/src/typescript-internal.d.ts
@@ -35,6 +35,10 @@ declare module "typescript" {
         parent?: Symbol;
     }
 
+    interface Signature {
+        compositeSignatures?: Signature[];
+    }
+
     function transformJsx(context: TransformationContext): (x: SourceFile) => SourceFile;
 
     export type OuterExpression =
diff --git a/test/unit/functions/validation/invalidFunctionAssignments.spec.ts b/test/unit/functions/validation/invalidFunctionAssignments.spec.ts
index caf3576a7..95b26b7d0 100644
--- a/test/unit/functions/validation/invalidFunctionAssignments.spec.ts
+++ b/test/unit/functions/validation/invalidFunctionAssignments.spec.ts
@@ -226,3 +226,18 @@ test.each([
         let f: ${assignType} = o;
     `.expectDiagnosticsToMatchSnapshot([unsupportedOverloadAssignment.code], true);
 });
+
+// https://github.com/TypeScriptToLua/TypeScriptToLua/issues/896
+test("Does not fail on union type signatures (#896)", () => {
+    util.testExpression`foo<'a'>(() => {});`
+        .setTsHeader(
+            `
+        declare interface Events {
+            a(): void;
+            [key: string]: (this: void) => void;
+        }      
+        declare function foo<T extends 'a' | 'b'>(callback: Events[T]): void;
+    `
+        )
+        .expectToHaveDiagnostics([unsupportedOverloadAssignment.code]);
+});
diff --git a/test/unit/functions/validation/validFunctionAssignments.spec.ts b/test/unit/functions/validation/validFunctionAssignments.spec.ts
index 8c98196d9..7a68d0ea6 100644
--- a/test/unit/functions/validation/validFunctionAssignments.spec.ts
+++ b/test/unit/functions/validation/validFunctionAssignments.spec.ts
@@ -233,3 +233,18 @@ test.each([
         return f(${args.map(a => '"' + a + '"').join(", ")});
     `.expectToMatchJsResult();
 });
+
+// https://github.com/TypeScriptToLua/TypeScriptToLua/issues/896
+test("Does not fail on union type signatures (#896)", () => {
+    util.testExpression`foo<'a'>(() => {});`
+        .setTsHeader(
+            `
+        declare interface Events {
+            a(): void;
+            [key: string]: Function;
+        }      
+        declare function foo<T extends 'a' | 'b'>(callback: Events[T]): void;
+    `
+        )
+        .expectToHaveNoDiagnostics();
+});