diff --git a/src/Declaration.js b/src/Declaration.js
index 74c39c2..abe86b5 100644
--- a/src/Declaration.js
+++ b/src/Declaration.js
@@ -37,7 +37,7 @@ export default class Declaration {
 		this.tested = true;
 
 		if ( !this.statement || !this.functionNode ) {
-			this.hasSideEffects = false;
+			this.hasSideEffects = true; // err on the side of caution. TODO handle unambiguous `var x; x = y => z` cases
 		} else {
 			this.hasSideEffects = testForSideEffects( this.functionNode.body, this.functionNode._scope, this.statement, strongDependencies );
 		}
diff --git a/test/form/side-effect-e/_config.js b/test/form/side-effect-e/_config.js
index a8d5bf9..225bacd 100644
--- a/test/form/side-effect-e/_config.js
+++ b/test/form/side-effect-e/_config.js
@@ -1,5 +1,5 @@
 module.exports = {
-	description: 'excludes functions that are known to be pure',
+	description: 'accounts for local scopes when tested function purity',
 	options: {
 		moduleName: 'myBundle'
 	}
diff --git a/test/form/side-effect-j/_config.js b/test/form/side-effect-j/_config.js
new file mode 100644
index 0000000..91550c0
--- /dev/null
+++ b/test/form/side-effect-j/_config.js
@@ -0,0 +1,6 @@
+module.exports = {
+	description: 'includes late function declarations with side-effects',
+	options: {
+		moduleName: 'myBundle'
+	}
+};
diff --git a/test/form/side-effect-j/_expected/amd.js b/test/form/side-effect-j/_expected/amd.js
new file mode 100644
index 0000000..85bce30
--- /dev/null
+++ b/test/form/side-effect-j/_expected/amd.js
@@ -0,0 +1,5 @@
+define(function () { 'use strict';
+
+	
+
+});
diff --git a/test/form/side-effect-j/_expected/cjs.js b/test/form/side-effect-j/_expected/cjs.js
new file mode 100644
index 0000000..ad9a93a
--- /dev/null
+++ b/test/form/side-effect-j/_expected/cjs.js
@@ -0,0 +1 @@
+'use strict';
diff --git a/test/form/side-effect-j/_expected/es6.js b/test/form/side-effect-j/_expected/es6.js
new file mode 100644
index 0000000..e69de29
diff --git a/test/form/side-effect-j/_expected/iife.js b/test/form/side-effect-j/_expected/iife.js
new file mode 100644
index 0000000..e69de29
diff --git a/test/form/side-effect-j/_expected/umd.js b/test/form/side-effect-j/_expected/umd.js
new file mode 100644
index 0000000..e69de29
diff --git a/test/form/side-effect-j/foo.js b/test/form/side-effect-j/foo.js
new file mode 100644
index 0000000..2f4073f
--- /dev/null
+++ b/test/form/side-effect-j/foo.js
@@ -0,0 +1,4 @@
+var augment;
+augment = x => x.augmented = true;
+
+export { augment };
diff --git a/test/form/side-effect-j/main.js b/test/form/side-effect-j/main.js
new file mode 100644
index 0000000..3032b85
--- /dev/null
+++ b/test/form/side-effect-j/main.js
@@ -0,0 +1,4 @@
+import { augment } from './foo.js';
+
+export default function x () {}
+augment( x );