diff --git a/src/Bundle.js b/src/Bundle.js
index b41a6bd..1b9834e 100644
--- a/src/Bundle.js
+++ b/src/Bundle.js
@@ -58,9 +58,7 @@ export default class Bundle {
 					const declaration = entryModule.traceExport( name );
 					declaration.isExported = true;
 
-					if ( declaration.statement ) {
-						declaration.statement.mark();
-					}
+					if ( declaration.statement ) declaration.use();
 				});
 
 				let settled = false;
diff --git a/src/ExternalModule.js b/src/ExternalModule.js
index 81a1a17..f0d3408 100644
--- a/src/ExternalModule.js
+++ b/src/ExternalModule.js
@@ -6,8 +6,6 @@ class ExternalDeclaration {
 		this.module = module;
 		this.name = name;
 		this.isExternal = true;
-
-		this.references = [];
 	}
 
 	addReference ( reference ) {
@@ -31,6 +29,10 @@ class ExternalDeclaration {
 
 		return es6 ? this.name : `${this.module.name}.${this.name}`;
 	}
+
+	use () {
+		// noop?
+	}
 }
 
 export default class ExternalModule {
diff --git a/src/Module.js b/src/Module.js
index dd67cf0..18670b2 100644
--- a/src/Module.js
+++ b/src/Module.js
@@ -14,12 +14,11 @@ class SyntheticDefaultDeclaration {
 		this.statement = statement;
 		this.name = name;
 
-		this.references = [];
+		this.original = null;
+		this.isExported = false;
 	}
 
 	addReference ( reference ) {
-		this.references.push( reference );
-
 		reference.declaration = this;
 		this.name = reference.name;
 	}
@@ -33,6 +32,11 @@ class SyntheticDefaultDeclaration {
 			this.name :
 			this.original.render();
 	}
+
+	use () {
+		this.isUsed = true;
+		this.statement.mark();
+	}
 }
 
 class SyntheticNamespaceDeclaration {
@@ -40,7 +44,6 @@ class SyntheticNamespaceDeclaration {
 		this.module = module;
 		this.name = null;
 
-		this.references = [];
 		this.needsNamespaceBlock = false;
 
 		this.originals = blank();
@@ -72,12 +75,10 @@ class SyntheticNamespaceDeclaration {
 
 			keys( this.originals ).forEach( name => {
 				const original = this.originals[ name ];
-				original.statement.mark();
+				original.use();
 			});
 		}
 
-		this.references.push( reference );
-
 		reference.declaration = this;
 		this.name = reference.name;
 	}
@@ -99,6 +100,10 @@ class SyntheticNamespaceDeclaration {
 	render () {
 		return this.name;
 	}
+
+	use () {
+		// noop
+	}
 }
 
 export default class Module {
@@ -581,7 +586,7 @@ export default class Module {
 					const defaultName = defaultDeclaration.render();
 
 					// prevent `var undefined = sideEffectyDefault(foo)`
-					if ( !defaultDeclaration.isExported && !defaultDeclaration.references.length ) {
+					if ( !defaultDeclaration.isExported && !defaultDeclaration.isUsed ) {
 						magicString.remove( statement.start, statement.node.declaration.start );
 						return;
 					}
diff --git a/src/Statement.js b/src/Statement.js
index bf35eba..27f1f36 100644
--- a/src/Statement.js
+++ b/src/Statement.js
@@ -155,9 +155,7 @@ export default class Statement {
 		this.isIncluded = true;
 
 		this.references.forEach( reference => {
-			if ( reference.declaration && reference.declaration.statement ) {
-				reference.declaration.statement.mark();
-			}
+			if ( reference.declaration ) reference.declaration.use();
 		});
 	}
 
diff --git a/src/ast/Scope.js b/src/ast/Scope.js
index 2e6a543..64c90be 100644
--- a/src/ast/Scope.js
+++ b/src/ast/Scope.js
@@ -35,7 +35,6 @@ function extractNames ( param ) {
 
 class Declaration {
 	constructor () {
-		this.references = [];
 		this.statement = null;
 		this.name = null;
 
@@ -55,6 +54,11 @@ class Declaration {
 
 		return `exports.${this.name}`;
 	}
+
+	use () {
+		this.isUsed = true;
+		if ( this.statement ) this.statement.mark();
+	}
 }
 
 export default class Scope {