From 9535f94e389911417990351b0e75e2595b1e6b32 Mon Sep 17 00:00:00 2001
From: Thomas Fussell <thomas.fussell@gmail.com>
Date: Sat, 25 Feb 2017 08:54:38 -0600
Subject: [PATCH] don't attempt to garbage collect cells without formulae,
 closes #121

---
 source/cell/cell.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/source/cell/cell.cpp b/source/cell/cell.cpp
index 0dd78fd0..797c170c 100644
--- a/source/cell/cell.cpp
+++ b/source/cell/cell.cpp
@@ -490,8 +490,11 @@ std::string cell::formula() const
 
 void cell::clear_formula()
 {
-    d_->formula_.clear();
-    worksheet().garbage_collect_formulae();
+    if (has_formula())
+    {
+        d_->formula_.clear();
+        worksheet().garbage_collect_formulae();
+    }
 }
 
 void cell::error(const std::string &error)