Migrated to AndroidX, can't build anymore

I migrated to AndroidX and ever since then MaterialDesignLibrary prevents me from building successfully. I currently keep getting this error which I don't get when I comment out MaterialDesignLibrary from my gradle file.

> ERROR: Unable to resolve dependency for ':app@googlePlayFlavorDebug/compileClasspath': Could not resolve com.android.support:support-v4:22.+.