diff --git a/lib/program.js b/lib/program.js
index 47df371..6c26821 100644
--- a/lib/program.js
+++ b/lib/program.js
@@ -90,13 +90,12 @@ function Program(options) {
   this.isRxvt = /rxvt/i.test(process.env.COLORTERM);
   this.isXterm = false;
 
-  this.isTMUX = this.term('screen') && !!process.env.TMUX;
-
+  this.tmux = !!process.env.TMUX;
   this.tmuxVersion = (function() {
-    if (!process.env.TMUX) return 2;
+    if (!self.tmux) return 2;
     try {
       version = cp.execFileSync('tmux', ['-V'], { encoding: 'utf8' });
-      return +version.trim().split(/\s+/).pop() || 2;
+      return +/([\d.]+)/.exec(version)[1];
     } catch (e) {
       return 2;
     }
@@ -1496,9 +1495,9 @@ Program.prototype._write = function(text) {
 // Example: `DCS tmux; ESC Pt ST`
 // Real: `DCS tmux; ESC Pt ESC \`
 Program.prototype._twrite = function(data) {
-  if (process.env.TMUX) data = '\x1bPtmux;\x1b' + data + '\x1b\\';
+  if (this.tmux) data = '\x1bPtmux;\x1b' + data + '\x1b\\';
   // Should work but tmux doesn't implement ST correctly:
-  // if (process.env.TMUX) data = '\x1bPtmux;\x1b' + data + '\x07';
+  // if (this.tmux) data = '\x1bPtmux;\x1b' + data + '\x07';
   return this._write(data);
 };
 
@@ -2025,7 +2024,7 @@ Program.prototype.setTitle = function(title) {
 
   // if (this.term('screen')) {
   //   // Tmux pane
-  //   // if (process.env.TMUX) {
+  //   // if (this.tmux) {
   //   //   return this._write('\x1b]2;' + title + '\x1b\\');
   //   // }
   //   return this._write('\x1bk' + title + '\x1b\\');
@@ -3137,9 +3136,15 @@ Program.prototype.enableMouse = function() {
     return this.setMouse(options, true);
   }
 
+  // NOTE:
+  // Cell Motion isn't normally need for anything below here, but we'll
+  // activate it for tmux (whether using it or not) in case our all-motion
+  // passthrough does not work. It can't hurt.
+
   if (this.term('rxvt-unicode')) {
     return this.setMouse({
       urxvtMouse: true,
+      cellMotion: true,
       allMotion: true
     }, true);
   }
@@ -3149,6 +3154,7 @@ Program.prototype.enableMouse = function() {
     return this.setMouse({
       vt200Mouse: true,
       x10Mouse: true,
+      cellMotion: true,
       allMotion: true
     }, true);
   }
@@ -3160,6 +3166,7 @@ Program.prototype.enableMouse = function() {
     return this.setMouse({
       // NOTE: Could also use urxvtMouse here.
       sgrMouse: true,
+      cellMotion: true,
       allMotion: true
     }, true);
   }
@@ -3177,6 +3184,7 @@ Program.prototype.enableMouse = function() {
     return this.setMouse({
       vt200Mouse: true,
       utfMouse: true,
+      cellMotion: true,
       allMotion: true
     }, true);
   }
@@ -3260,7 +3268,7 @@ Program.prototype.setMouse = function(opt, enable) {
   if (opt.allMotion != null) {
     // NOTE: Latest versions of tmux seem to only support cellMotion (not
     // allMotion). We pass all motion through to the terminal.
-    if (process.env.TMUX && this.tmuxVersion >= 2) {
+    if (this.tmux && this.tmuxVersion >= 2) {
       if (opt.allMotion) this._twrite('\x1b[?1003h');
       else this._twrite('\x1b[?1003l');
     } else {