diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8fb27893..b06dc6bf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -105,6 +105,8 @@
 * A multi-column character that does not fit on the current line is
   now printed on the next line, instead of only printing half the
   character.
+* Font size can no longer be reduced to negative values
+  (https://codeberg.org/dnkl/foot/issues/38).
 
 
 ### Security
diff --git a/terminal.c b/terminal.c
index 40bfbc90..84c9d459 100644
--- a/terminal.c
+++ b/terminal.c
@@ -1430,7 +1430,7 @@ term_font_size_adjust(struct terminal *term, double amount)
             old_pt_size = term->font_sizes[i].px_size * 72. / dpi;
         }
 
-        term->font_sizes[i].pt_size = old_pt_size + amount;
+        term->font_sizes[i].pt_size = fmax(old_pt_size + amount, 0);
         term->font_sizes[i].px_size = -1;
     }