Error 1 for Mrbayes

If this happens to you when trying to compile MrBayes:

% make
gcc -DUNIX_VERSION -DUSE_READLINE -O3 -Wall    -c -o mb.o mb.c
gcc -DUNIX_VERSION -DUSE_READLINE -O3 -Wall    -c -o mcmc.o mcmc.c
gcc -DUNIX_VERSION -DUSE_READLINE -O3 -Wall    -c -o bayes.o bayes.c
bayes.c:45:31: readline/readline.h: No such file or directory
bayes.c:46:30: readline/history.h: No such file or directory
bayes.c: In function `main':
bayes.c:189: error: `rl_attempted_completion_function' undeclared (first use in this function)
bayes.c:189: error: (Each undeclared identifier is reported only once
bayes.c:189: error: for each function it appears in.)
bayes.c: In function `CommandLine':
bayes.c:311: warning: implicit declaration of function `readline'
bayes.c:311: warning: assignment makes pointer from integer without a cast
bayes.c:316: warning: implicit declaration of function `add_history'
bayes.c: In function `readline_completion':
bayes.c:386: warning: implicit declaration of function `rl_completion_matches'
bayes.c:386: warning: assignment makes pointer from integer without a cast
make: *** [bayes.o] Error 1

This means that make can't find readline. Comment that line out and go round again.