From 3f9b3fd4e237fe76112eb389594ace00ba26e8f3 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <tahvdbrand@gmail.com>
Date: Wed, 19 Feb 2025 16:37:57 +0100
Subject: [PATCH 1/2] avoid dividing by zero

---
 R/position-stack.R | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/R/position-stack.R b/R/position-stack.R
index de23456625..0e35f1191e 100644
--- a/R/position-stack.R
+++ b/R/position-stack.R
@@ -224,7 +224,10 @@ pos_stack <- function(df, width, vjust = 1, fill = FALSE) {
   heights <- c(0, cumsum(y))
 
   if (fill) {
-    heights <- heights / abs(heights[length(heights)])
+    total <- abs(heights[length(heights)])
+    if (total > sqrt(.Machine$double.eps)) {
+      heights <- heights / total
+    }
   }
 # We need to preserve ymin/ymax order. If ymax is lower than ymin in input, it should remain that way
   if (!is.null(df$ymin) && !is.null(df$ymax)) {

From c90b6a34434fcad8a887b509004bf09c8a30ca24 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <tahvdbrand@gmail.com>
Date: Wed, 19 Feb 2025 16:44:28 +0100
Subject: [PATCH 2/2] add news bullet

---
 NEWS.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/NEWS.md b/NEWS.md
index 74b049ace5..94644036eb 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,6 @@
 # ggplot2 (development version)
 
+* `position_fill()` avoids stacking observations of zero (@teunbrand, #6338)
 * New parameters for `geom_label()` (@teunbrand and @steveharoz, #5365):
   * The `linewidth` aesthetic is now applied and replaces the `label.size` 
     argument.