Error building executable gem: error compiling squash.c

[soumyaray]

Trying to build an executable gem. The error message I get when it crashes:

compiling miniprelude.c
compiling autoupdate_autoupdate.c
compiling autoupdate_exepath.c
compiling autoupdate_inflate.c
compiling autoupdate_tmpf.c
compiling autoupdate_utils.c
compiling squash_cache.c
compiling squash_decompress.c
compiling squash_dir.c
squash_dir.c:479:2: error: implicitly declaring library function 'free' with type 'void (void *)' [-Werror,-Wimplicit-function-declaration]
        free(path0);
        ^
squash_dir.c:479:2: note: include the header <stdlib.h> or explicitly provide a declaration for 'free'
1 error generated.
make: *** [squash_dir.o] Error 1
Failed running [{"CI"=>"true", "ENCLOSE_IO_USE_ORIGINAL_RUBY"=>"1", "CFLAGS"=>" -fPIC -O3 -fno-fast-math -ggdb3 -Os -fdata-sections -ffunction-sections -pipe  -I/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/zlib  -I/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/openssl/include  -I/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/gdbm/build/include  -I/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/yaml/build/include  -I/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/libffi/build/lib/libffi-3.2.1/include  -I/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/ncurses/build/include  -I/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/readline/build/include ", "LDFLAGS"=>" -L/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/zlib /var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/zlib/libz.a  -L/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/openssl  -L/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/gdbm/build/lib  -L/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/yaml/build/lib  -L/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/libffi/build/lib  -L/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/ncurses/build/lib  -L/var/folders/vn/gm5v6xsn65v5ct5nj1jl3n540000gn/T/rubyc/readline/build/lib ", "ENCLOSE_IO_RUBYC_1ST_PASS"=>"1", "ENCLOSE_IO_RUBYC_2ND_PASS"=>nil}, "make -j4 -j1"]