diff --git a/src/containers/brush-mode.jsx b/src/containers/brush-mode.jsx
index 3142529b..bf1b372a 100644
--- a/src/containers/brush-mode.jsx
+++ b/src/containers/brush-mode.jsx
@@ -80,7 +80,7 @@ BrushMode.propTypes = {
     colorState: PropTypes.shape({
         fillColor: PropTypes.string.isRequired,
         strokeColor: PropTypes.string.isRequired,
-        strokeWidth: PropTypes.string.isRequired
+        strokeWidth: PropTypes.number.isRequired
     }).isRequired,
     handleMouseDown: PropTypes.func.isRequired,
     isBrushModeActive: PropTypes.bool.isRequired,
diff --git a/src/containers/line-mode.jsx b/src/containers/line-mode.jsx
index d1f00b0c..35e47b53 100644
--- a/src/containers/line-mode.jsx
+++ b/src/containers/line-mode.jsx
@@ -272,7 +272,7 @@ LineMode.propTypes = {
     colorState: PropTypes.shape({
         fillColor: PropTypes.string.isRequired,
         strokeColor: PropTypes.string.isRequired,
-        strokeWidth: PropTypes.string.isRequired
+        strokeWidth: PropTypes.number.isRequired
     }).isRequired,
     handleMouseDown: PropTypes.func.isRequired,
     isLineModeActive: PropTypes.bool.isRequired,