diff --git a/ps_graph.c b/ps_graph.c
index 5249a1d..85ac994 100644
--- a/ps_graph.c
+++ b/ps_graph.c
@@ -39,8 +39,8 @@ void ps_export_graph(FILE *file, struct expr_node *node, struct graph_range *ran
 
     for (i = -HALF_GRAPH_SIZE; i <= HALF_GRAPH_SIZE; i += GRID_STEP) {
         double inorm = (double)i / (double)GRAPH_SIZE + 0.5;
-        double xval = range->xmax * inorm + range->xmin * (1.0 - inorm) ; // range->xmin + inorm * (range->xmax - range->xmin);
-        double yval = range->ymax * inorm + range->ymin * (1.0 - inorm) ; // range->xmin + inorm * (range->xmax - range->xmin);
+        double xval = range->xmax * inorm + range->xmin * (1.0 - inorm); 
+        double yval = range->ymax * inorm + range->ymin * (1.0 - inorm); 
         
         fprintf(file,
             "newpath\n"
@@ -88,10 +88,18 @@ void ps_export_graph(FILE *file, struct expr_node *node, struct graph_range *ran
     );
 
     for (x = range->xmin; x <= range->xmax; x += range->step) {
+        const char *cmd = "lineto";
+        double xpos, ypos;
         double y = node_eval(node, x);
-        double xpos = (double)(-HALF_GRAPH_SIZE) + (x - range->xmin) / (range->xmax - range->xmin) * (double)GRAPH_SIZE;
-        double ypos = (double)(-HALF_GRAPH_SIZE) + (y - range->ymin) / (range->ymax - range->ymin) * (double)GRAPH_SIZE;
-        const char* cmd = "lineto";
+       
+        if (y != y) {
+            first = 1;
+            continue;
+        }
+
+        xpos = (double)(-HALF_GRAPH_SIZE) + (x - range->xmin) / (range->xmax - range->xmin) * (double)GRAPH_SIZE;
+        ypos = (double)(-HALF_GRAPH_SIZE) + (y - range->ymin) / (range->ymax - range->ymin) * (double)GRAPH_SIZE;
+        
         if (first) {
             cmd = "moveto";
             first = 0;