I receive this error upon issuing the make command:

gui.o: In function `GUI::GUI[not-in-charge](char const*)':
gui.o(.text+0x44a2): undefined reference to `Fl_File_Icon::load_system_icons()'
gui.o: In function `GUI::GUI[in-charge](char const*)':
gui.o(.text+0x8af2): undefined reference to `Fl_File_Icon::load_system_icons()'
htmldoc.o: In function `main':
htmldoc.o(.text+0x2afc): undefined reference to `Fl_File_Icon::load_system_icons()'
collect2: ld returned 1 exit status
make[1]: *** [htmldoc] Error 1

If you have any suggestions, please respond.

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