diff --git a/modules/firefox/each-config.nix b/modules/firefox/each-config.nix
index e046b9c9..79c1e0ef 100644
--- a/modules/firefox/each-config.nix
+++ b/modules/firefox/each-config.nix
@@ -43,6 +43,15 @@ mkTarget {
             "font.name.monospace.x-western" = fonts.monospace.name;
             "font.name.sans-serif.x-western" = fonts.sansSerif.name;
             "font.name.serif.x-western" = fonts.serif.name;
+
+            # 4/3 factor used for pt to px;
+            # adding 0.5 before flooring for rounding as Firefox requires an int
+            "font.size.monospace.x-western" = builtins.floor (
+              (fonts.sizes.terminal * 4.0 / 3.0) + 0.5
+            );
+            "font.size.variable.x-western" = builtins.floor (
+              (fonts.sizes.applications * 4.0 / 3.0) + 0.5
+            );
           };
         });
       }