diff --git a/core/src/processing/core/PApplet.java b/core/src/processing/core/PApplet.java
index cb84f67c8..af28a975d 100644
--- a/core/src/processing/core/PApplet.java
+++ b/core/src/processing/core/PApplet.java
@@ -4921,7 +4921,13 @@ public class PApplet implements PConstants {
   public final float random(float low, float high) {
     if (low >= high) return low;
     float diff = high - low;
-    return random(diff) + low;
+    float value = 0;
+    // because of rounding error, can't just add low, otherwise it may hit high
+    // https://github.com/processing/processing/issues/4551
+    do {
+      value = random(diff) + low;
+    } while (value == high);
+    return value;
   }
 
 
diff --git a/core/todo.txt b/core/todo.txt
index e90cc9304..6fa4d2f77 100644
--- a/core/todo.txt
+++ b/core/todo.txt
@@ -1,6 +1,8 @@
 0241 (3.1.2)
 X rewrite csv handling
 X   fix parsing bugs, remove newlines option, improve performance
+X prevent random(low, high) from returning 'high'
+X   https://github.com/processing/processing/issues/4551
 
 gohai
 X Fix GLExceptions on Raspberry Pi when using offscreen PGraphics