diff --git a/README.md b/README.md
index c79d21a0..90e01b9c 100644
--- a/README.md
+++ b/README.md
@@ -11,11 +11,11 @@ Supported Attributes
 
 Name | Value
 ----:|------
-width, height | number
+width, height | positive number
 left, right, top, bottom | number
 margin, marginLeft, marginRight, marginTop, marginBottom | number
-padding, paddingLeft, paddingRight, paddingTop, paddingBottom | number
-borderWidth, borderLeftWidth, borderRightWidth, borderTopWidth, borderBottomWidth | number
+padding, paddingLeft, paddingRight, paddingTop, paddingBottom | positive number
+borderWidth, borderLeftWidth, borderRightWidth, borderTopWidth, borderBottomWidth | positive number
 flexDirection | 'column', 'row'
 justifyContent | 'flex-start', 'center', 'flex-end', 'space-between', 'space-around'
 alignItems, alignSelf | 'flex-start', 'center', 'flex-end', 'stretch'