diff --git a/lib/actions/ui.js b/lib/actions/ui.js
index 6e3ac9e2..54f22b11 100644
--- a/lib/actions/ui.js
+++ b/lib/actions/ui.js
@@ -70,7 +70,8 @@ export function decreaseFontSize() {
       effect() {
         const state = getState();
         const old = state.ui.fontSizeOverride || state.ui.fontSize;
-        const value = old - 1;
+        // when the font-size is really small, below 5px, xterm starts showing up issues.
+        const value = old > 5 ? old - 1 : old;
         dispatch({
           type: UI_FONT_SIZE_SET,
           value