diff --git a/src/parsing/textShadow.js b/src/parsing/textShadow.js
index bc2b056..23f47d1 100644
--- a/src/parsing/textShadow.js
+++ b/src/parsing/textShadow.js
@@ -13,8 +13,8 @@ export type TextShadow = {
 const TEXT_SHADOW_PROPERTY = /((rgba|rgb)\([^\)]+\)(\s-?\d+px){3})/g;
 const TEXT_SHADOW_VALUES = /(-?\d+px)|(#.+)|(rgb\(.+\))|(rgba\(.+\))/g;
 
-export const parseTextShadow = (textShadow: string): Array<TextShadow> | null => {
-    if (textShadow === 'none') {
+export const parseTextShadow = (textShadow: ?string): Array<TextShadow> | null => {
+    if (textShadow === 'none' || typeof(textShadow) !== 'string') {
         return null;
     }
 
diff --git a/src/parsing/transform.js b/src/parsing/transform.js
index a4bcf71..b92892e 100644
--- a/src/parsing/transform.js
+++ b/src/parsing/transform.js
@@ -31,10 +31,11 @@ const parseTransformOrigin = (origin: string): TransformOrigin => {
     return [values[0], values[1]];
 };
 
-const parseTransformMatrix = (transform: string): Matrix | null => {
-    if (transform === 'none') {
+const parseTransformMatrix = (transform: ?string): Matrix | null => {
+    if (transform === 'none' || typeof(transform) !== 'string') {
         return null;
     }
+
     const match = transform.match(MATRIX);
     if (match) {
         if (match[1] === 'matrix') {