diff --git a/book/plots/fig-temperature-ambient.tex b/book/plots/fig-temperature-ambient.tex
index c3d876f..9ca4351 100644
--- a/book/plots/fig-temperature-ambient.tex
+++ b/book/plots/fig-temperature-ambient.tex
@@ -6,6 +6,7 @@
         major grid style={line width=.2pt,draw=gray!30},
         axis x line=middle,
         axis y line=middle,
+        axis line style={-Latex},
         width=\textwidth,
         height=0.5\textwidth,
         xmax=35, xmin=-0.1,
diff --git a/book/plots/fig-temperature-surface.tex b/book/plots/fig-temperature-surface.tex
index 8ddaf9e..a0a2090 100644
--- a/book/plots/fig-temperature-surface.tex
+++ b/book/plots/fig-temperature-surface.tex
@@ -6,6 +6,7 @@
         major grid style={line width=.2pt,draw=gray!30},
         axis x line=middle,
         axis y line=middle,
+        axis line style={-Latex},
         width=\textwidth,
         height=0.5\textwidth,
         xmax=35, xmin=-0.1,
diff --git a/book/plots/fig-yeast-sourdough-strength.tex b/book/plots/fig-yeast-sourdough-strength.tex
index defaa62..77c34a5 100644
--- a/book/plots/fig-yeast-sourdough-strength.tex
+++ b/book/plots/fig-yeast-sourdough-strength.tex
@@ -7,6 +7,7 @@
                 \qty{60}{\percent}~hydration},
         axis x line=middle,
         axis y line=middle,
+        axis line style={-Latex},
         width=\textwidth,
         height=0.5\textwidth,
         xmax=44, xmin=-0.1,