diff --git a/criticals.c b/criticals.c
index 8111232..86b509f 100644
--- a/criticals.c
+++ b/criticals.c
@@ -17,18 +17,17 @@
 #include "criticals.h"
 #include "util.h"
 
-size_t newton_iters = 100;
-
 static size_t idx = 0;
 static long double complex criticals[100];
 
 int
 behaves_critical(long double complex (*df)(long double complex),
     long double complex (*ddf)(long double complex), long double complex z,
-    long double complex *crit, long double bailout, long double epsilon)
+    long double complex *crit, long niters, long double bailout,
+    long double epsilon)
 {
-	size_t i;
-	for (i = 0; i < newton_iters && cabsl(z) < bailout; i++)
+	long i;
+	for (i = 0; i < niters && cabsl(z) < bailout; i++)
 		z = z - df(z) / ddf(z);
 
 	if (cabsl(df(z)) < epsilon) {
diff --git a/criticals.h b/criticals.h
index 2aa2417..5d13a40 100644
--- a/criticals.h
+++ b/criticals.h
@@ -15,7 +15,7 @@
 
 int behaves_critical(long double complex (*)(long double complex),
     long double complex (*)(long double complex), long double complex,
-    long double complex *, long double, long double);
+    long double complex *, long, long double, long double);
 void add_critical_point(long double complex);
 size_t ncriticals(void);
 long double complex get_critical(size_t);
diff --git a/julia.c b/julia.c
index c2c887f..4dcf007 100644
--- a/julia.c
+++ b/julia.c
@@ -28,12 +28,14 @@
 
 #include "fun.h"
 
+#define OPTSTRING "a:b:c:D:d:h:Ll:N:n:w:x:y:z:"
+
 struct color contour_color = { 0 };
 static long double bailout = 1e100,
     epsilon = 1e-8,
     sec_w = 4.0,
     contour = 0.0005L;
-static long niters = 250;
+static long niters = 250, newton_iters = 100;
 
 static void
 print_critical_points(void)
@@ -103,7 +105,8 @@ usage(void)
 	fprintf(stderr, "Usage: %s julia [-L] [-x julia_x] [-y julia_y]\n"
 	    "    [-n niters] [-h height] [-w width] [-z zoom]\n"
 	    "    [-a center_x] [-b center_y] [-l light_intensity]\n"
-	    "    [-d density] [-c contour] [-D displacement]\n",
+	    "    [-d density] [-c contour] [-D displacement]\n"
+	    "    [-N newton_iters]\n",
 	    xgetprogname());
 	exit(1);
 }
@@ -134,7 +137,7 @@ julia_main(int argc, char *argv[])
 	    i, j;
 	int ch, do_light = 0;
 
-	while ((ch = getopt(argc, argv, "a:b:c:D:d:h:Ll:n:w:x:y:z:")) != -1)
+	while ((ch = getopt(argc, argv, OPTSTRING)) != -1)
 		switch (ch) {
 		case 'a':
 			cen_x = parse_double(optarg);
@@ -160,6 +163,9 @@ julia_main(int argc, char *argv[])
 		case 'l':
 			light_intensity = parse_double(optarg);
 			break;
+		case 'N':
+			newton_iters = parse_integer(optarg, 1, LONG_MAX);
+			break;
 		case 'n':
 			niters = parse_integer(optarg, 1, LONG_MAX);
 			break;
@@ -205,8 +211,8 @@ julia_main(int argc, char *argv[])
 		for (j = 0; j < width; j++) {
 			zx = cen_x + (j / (long double)width - 0.5L) * sec_w;
 			z = zx + I * zy;
-			if (behaves_critical(df, ddf, z, &crit, bailout,
-			    epsilon))
+			if (behaves_critical(df, ddf, z, &crit, newton_iters,
+			    bailout, epsilon))
 				add_critical_point(crit);
 		}
 	}