ggplot2 adds backticks around variable labels if those variables contain a space and the aesthetics are defined in the geom and not globally. No backticks: ``` r library(ggplot2) data <- tibble::tibble( "variable with space" = 1:5 ) ggplot(data) + aes(x = `variable with space`, y = `variable with space`) + geom_point() ```  <sup>Created on 2019-03-14 by the [reprex package](https://reprex.tidyverse.org) (v0.2.1)</sup> Backticks: ``` r library(ggplot2) data <- tibble::tibble( "variable with space" = 1:5 ) ggplot(data) + geom_point(aes(x = `variable with space`, y = `variable with space`)) ```  <sup>Created on 2019-03-14 by the [reprex package](https://reprex.tidyverse.org) (v0.2.1)</sup>