R-Travis package build error - "there is no package 'dplyr'"

I'm building a package and every when through devtools testing fine, but I'm getting the following error from Travis:

Building with: R CMD build 
0.69s$ R CMD build  .
* checking for file ‘./DESCRIPTION’ ... OK
* preparing ‘fars2’:
* checking DESCRIPTION meta-information ... OK
* installing the package to build vignettes
      -----------------------------------
* installing *source* package ‘fars2’ ...
** R
** preparing package for lazy loading
Error in loadNamespace(j <- i[[1L]], c(lib.loc, .libPaths()), versionCheck = vI[[j]]) : 
  there is no package called ‘dplyr’
ERROR: lazy loading failed for package ‘fars2’
* removing ‘/tmp/RtmpUWHd2D/Rinst3a4038a68aec/fars2’
      -----------------------------------
ERROR: package installation failed

My DESCRIPTION file:

Package: fars2
Type: Package
Title: Fatality Analysis Reporting System Data Manager
Version: 0.1.0
Author: Michael Conway
Maintainer: Michael Conway <mpconway@gmail.com>
Description: This package uploads, organizes and annalyzes Fatality Analysis Reporting System accident data. 
License: GPL (>= 3)
Encoding: UTF-8
LazyData: true
Imports: dplyr, 
         readr, 
         tidyr, 
         maps, 
         graphics
Suggests: knitr,
    rmarkdown,
    testthat
VignetteBuilder: knitr
RoxygenNote: 6.0.1

Any suggestions?