diff --git a/CHANGELOG.md b/CHANGELOG.md
index f5363df3..85bee4cb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 - Call garbage collector after removing a column to prevent stale cached values
 - Trying to remove a column that doesn't exist deletes the latest column
 - Keep big integer as integer instead of lossely casting to float [#874](https://github.com/PHPOffice/PhpSpreadsheet/pull/874)
+- Fix branch pruning handling of non boolean conditions [#1167](https://github.com/PHPOffice/PhpSpreadsheet/pull/1167)
 
 ## [1.9.0] - 2019-08-17
 
diff --git a/src/PhpSpreadsheet/Calculation/Calculation.php b/src/PhpSpreadsheet/Calculation/Calculation.php
index 923b19e9..3b0eb39c 100644
--- a/src/PhpSpreadsheet/Calculation/Calculation.php
+++ b/src/PhpSpreadsheet/Calculation/Calculation.php
@@ -3809,13 +3809,19 @@ class Calculation
             if ($this->branchPruningEnabled && isset($tokenData['onlyIf'])) {
                 $onlyIfStoreKey = $tokenData['onlyIf'];
                 $storeValue = $branchStore[$onlyIfStoreKey] ?? null;
+                $storeValueAsBool = ($storeValue === null) ?
+                    true : (bool) Functions::flattenSingleValue($storeValue);
                 if (is_array($storeValue)) {
                     $wrappedItem = end($storeValue);
                     $storeValue = end($wrappedItem);
                 }
 
-                if (isset($storeValue) && (($storeValue !== true)
-                    || ($storeValue === 'Pruned branch'))
+                if (isset($storeValue)
+                    && (
+                        !$storeValueAsBool
+                        || Functions::isError($storeValue)
+                        || ($storeValue === 'Pruned branch')
+                    )
                 ) {
                     // If branching value is not true, we don't need to compute
                     if (!isset($fakedForBranchPruning['onlyIf-' . $onlyIfStoreKey])) {
@@ -3838,12 +3844,17 @@ class Calculation
             if ($this->branchPruningEnabled && isset($tokenData['onlyIfNot'])) {
                 $onlyIfNotStoreKey = $tokenData['onlyIfNot'];
                 $storeValue = $branchStore[$onlyIfNotStoreKey] ?? null;
+                $storeValueAsBool = ($storeValue === null) ?
+                    true : (bool) Functions::flattenSingleValue($storeValue);
                 if (is_array($storeValue)) {
                     $wrappedItem = end($storeValue);
                     $storeValue = end($wrappedItem);
                 }
-                if (isset($storeValue) && ($storeValue
-                    || ($storeValue === 'Pruned branch'))
+                if (isset($storeValue)
+                    && (
+                        $storeValueAsBool
+                        || Functions::isError($storeValue)
+                        || ($storeValue === 'Pruned branch'))
                 ) {
                     // If branching value is true, we don't need to compute
                     if (!isset($fakedForBranchPruning['onlyIfNot-' . $onlyIfNotStoreKey])) {
diff --git a/tests/data/Calculation/Calculation.php b/tests/data/Calculation/Calculation.php
index 201df47a..73dc6dad 100644
--- a/tests/data/Calculation/Calculation.php
+++ b/tests/data/Calculation/Calculation.php
@@ -55,7 +55,14 @@ function calculationTestDataGenerator()
     $formula3 = '=IF(A4="take A", A3, B3)';
     $set8 = [4, $dataArray5, $formula3, 'E5', ['A3'], ['B3']];
 
-    return [$set0, $set1, $set2, $set3, $set4, $set5, $set6, $set7, $set8];
+    $dataArray6 = [
+        ['=IF(22,"a","b")']
+    ];
+    $set9 = ['a', $dataArray6, '=A1', 'A2'];
+
+    return [
+        $set0, $set1, $set2, $set3, $set4, $set5, $set6, $set7, $set8, $set9
+    ];
 }
 
 return calculationTestDataGenerator();