diff --git a/doc/man/man3/notcurses_plot.3.md b/doc/man/man3/notcurses_plot.3.md
index 92c733589..4563a3153 100644
--- a/doc/man/man3/notcurses_plot.3.md
+++ b/doc/man/man3/notcurses_plot.3.md
@@ -22,10 +22,11 @@ typedef struct ncplot_options {
   ncgridgeom_e gridtype;
   // independent variable is a contiguous range
   uint64_t rangex;
-  // y axis min and max. set both equal to 0
-  // for autodiscovery of range.
+  // y axis min and max. set both equal to 0 for
+  // use with range autodiscovery.
   int64_t miny, maxy;
   bool exponentialy;  // is y-axis exponential?
+  bool discoverrange;
 } ncplot_options;
 ```
 
@@ -44,6 +45,10 @@ typedef struct ncplot_options {
 
 # RETURN VALUES
 
+**ncplot_create** will return an error if **discoverrange** is set, and either
+**miny** or **maxy** are non-zero. It will also return an error if
+**maxy** < **miny**.
+
 **ncplot_plane** returns the **ncplane** on which the plot is drawn. It cannot
 fail.
 
diff --git a/include/notcurses/notcurses.h b/include/notcurses/notcurses.h
index ee7a1ea8d..0450f1c55 100644
--- a/include/notcurses/notcurses.h
+++ b/include/notcurses/notcurses.h
@@ -2531,10 +2531,11 @@ typedef struct ncplot_options {
   // of keys. for a time range, say the previous hour sampled with second
   // resolution, the independent variable would be the range [0..3600): 3600.
   uint64_t rangex;
-  // y axis min and max. set the two equal (to any stand-in value; 0 is
-  // recommended) for autodiscovery of range.
+  // y axis min and max. for autodiscovery, these both must be equal to 0,
+  // and detectrange must be additionally be set.
   int64_t miny, maxy;
   bool exponentialy;  // is y-axis exponential?
+  bool detectrange; // if set, miny must == maxy
 } ncplot_options;
 
 // Use the provided plane 'n' for plotting according to the options 'opts'.
diff --git a/python/src/notcurses/build_notcurses.py b/python/src/notcurses/build_notcurses.py
index 31c84d90d..325f95fe3 100644
--- a/python/src/notcurses/build_notcurses.py
+++ b/python/src/notcurses/build_notcurses.py
@@ -418,6 +418,7 @@ typedef struct ncplot_options {
   uint64_t rangex;
   int64_t miny, maxy;
   bool exponentialy;
+  bool detectrange;
 } ncplot_options;
 struct ncplot* ncplot_create(struct ncplane* n, const ncplot_options* opts);
 struct ncplane* ncplot_plane(struct ncplot* n);
diff --git a/src/lib/internal.h b/src/lib/internal.h
index 621656ed3..ad0c4b82b 100644
--- a/src/lib/internal.h
+++ b/src/lib/internal.h
@@ -155,9 +155,11 @@ typedef struct ncplot {
   uint64_t minchannel;
   bool vertical_indep;
   ncgridgeom_e gridtype;
-  uint64_t rangex;
+  int64_t windowbase; // first valid x value
+  uint64_t rangex; // windowbase + rangex - 1 -> last valid x
   int64_t miny, maxy;
   bool exponentialy;
+  bool detectrange;
 } ncplot;
 
 typedef struct ncmenu {
diff --git a/src/lib/plot.c b/src/lib/plot.c
index 4e454d681..fe516cc6b 100644
--- a/src/lib/plot.c
+++ b/src/lib/plot.c
@@ -1,6 +1,13 @@
 #include "internal.h"
 
 ncplot* ncplot_create(ncplane* n, const ncplot_options* opts){
+  // detectrange requires that miny == maxy
+  if(opts->detectrange && opts->miny != opts->maxy){
+    return NULL;
+  }
+  if(opts->maxy < opts->miny){
+    return NULL;
+  }
   ncplot* ret = malloc(sizeof(*ret));
   if(ret){
     ret->ncp = n;
@@ -12,6 +19,8 @@ ncplot* ncplot_create(ncplane* n, const ncplot_options* opts){
     ret->vertical_indep = opts->vertical_indep;
     ret->gridtype = opts->gridtype;
     ret->exponentialy = opts->exponentialy;
+    ret->windowbase = 0;
+    ret->detectrange = opts->detectrange;
   }
   return ret;
 }
@@ -20,14 +29,30 @@ ncplane* ncplot_plane(ncplot* n){
   return n->ncp;
 }
 
+static inline bool
+invalid_y(ncplot* n, int64_t y){
+  if(y > n->maxy || y < n->miny){
+    return true;
+  }
+  return false;
+}
+
 // Add to or set the value corresponding to this x. If x is beyond the current
 // x window, the x window is advanced to include x, and values passing beyond
 // the window are lost. The first call will place the initial window. The plot
 // will be redrawn, but notcurses_render() is not called.
-int ncplot_add_sample(struct ncplot* n, uint64_t x, int64_t y){
+int ncplot_add_sample(ncplot* n, uint64_t x, int64_t y){
+  if(invalid_y(n, y)){
+    return -1;
+  }
+  return 0;
 }
 
-int ncplot_set_sample(struct ncplot* n, uint64_t x, int64_t y){
+int ncplot_set_sample(ncplot* n, uint64_t x, int64_t y){
+  if(invalid_y(n, y)){
+    return -1;
+  }
+  return 0;
 }
 
 void ncplot_destroy(ncplot* n){