diff --git a/src/cmd/plot/plot.h b/src/cmd/plot/plot.h
new file mode 100644
index 0000000..81b41c9
--- /dev/null
+++ b/src/cmd/plot/plot.h
@@ -0,0 +1,35 @@
+/*
+ * Prototypes for libplot functions.
+ */
+void rarc(double, double, double, double, double, double, double);
+void box(double, double, double, double);
+void cfill(char *);
+void circ(double, double, double);
+void closepl(void);
+void color(char *);
+void plotdisc(double, double, double);
+void dpoint(double, double);
+void erase(void);
+void fill(int [], double *[]);
+void frame(double, double, double, double);
+void grade(double);
+void idle(void);
+void plotline(double, double, double, double);
+void move(double, double);
+void openpl(char *);
+void parabola(double, double, double, double, double, double);
+void pen(char *);
+void plotpoly(int [], double *[]);
+void ppause(void);
+void ptype(char *);
+void range(double, double, double, double);
+void restore(void);
+void rmove(double, double);
+void rvec(double, double);
+void sbox(double, double, double, double);
+void splin(int, int [], double *[]);
+void text(char *);
+void vec(double, double);
+void save(void);
+char *whoami(void);
+void doublebuffer(void);