diff --git a/lib/reducers/term-groups.js b/lib/reducers/term-groups.js
index a8bef8182edd..1ccf27e61177 100644
--- a/lib/reducers/term-groups.js
+++ b/lib/reducers/term-groups.js
@@ -5,6 +5,7 @@ import { SESSION_ADD, SESSION_SET_ACTIVE } from '../constants/sessions';
 import { findBySession } from '../utils/term-groups';
 import { decorateTermGroupsReducer } from '../utils/plugins';
 
+const MIN_SIZE = 0.05;
 const initialState = Immutable({
   termGroups: {},
   activeSessions: {},
@@ -172,6 +173,8 @@ const removeGroup = (state, uid) => {
 };
 
 const resizeGroup = (state, uid, sizes) => {
+  // Make sure none of the sizes fall below MIN_SIZE:
+  if (sizes.find(size => size < MIN_SIZE)) return state;
   return state.setIn(
     ['termGroups', uid, 'sizes'],
     sizes