Using an if statement with an agentset in NetLogo

New to NetLogo. I am using the Fire Simple example, I added new tress with the pcolor=blue. I am trying to make a condition that the blue patch will only turn red if its 4 surrounding neighbors are red as well.

ask patches with [pcolor = blue] [ set pcolor red if (neighbors4 with [pcolor = red] > 3) ]

I get an error "> expected this input to be an agent or number or string, but got an agentset instead"