diff --git a/src/App/Expression.cpp b/src/App/Expression.cpp
index 486100f45..657424397 100644
--- a/src/App/Expression.cpp
+++ b/src/App/Expression.cpp
@@ -455,17 +455,6 @@ std::string OperatorExpression::toString() const
     bool needsParens;
     Operator leftOperator(NONE), rightOperator(NONE);
 
-    switch (op) {
-    case NEG:
-        s << "-" << left->toString();
-        return s.str();
-    case POS:
-        s << "+" << left->toString();
-        return s.str();
-    default:
-        break;
-    }
-
     needsParens = false;
     if (freecad_dynamic_cast<OperatorExpression>(left))
         leftOperator = static_cast<OperatorExpression*>(left)->op;
@@ -478,6 +467,17 @@ std::string OperatorExpression::toString() const
         //    needsParens = true;
     }
 
+    switch (op) {
+    case NEG:
+        s << "-" << (needsParens ? "(" : "") << left->toString() << (needsParens ? ")" : "");
+        return s.str();
+    case POS:
+        s << "+" << (needsParens ? "(" : "") << left->toString() << (needsParens ? ")" : "");
+        return s.str();
+    default:
+        break;
+    }
+
     if (needsParens)
         s << "(" << left->toString() << ")";
     else
diff --git a/src/Mod/Spreadsheet/TestSpreadsheet.py b/src/Mod/Spreadsheet/TestSpreadsheet.py
index 2cd26b5be..105ef38c6 100644
--- a/src/Mod/Spreadsheet/TestSpreadsheet.py
+++ b/src/Mod/Spreadsheet/TestSpreadsheet.py
@@ -29,6 +29,7 @@ class SpreadsheetCases(unittest.TestCase):
     def testAggregates(self):
         """ Test all aggregate functions """
         sheet = self.doc.addObject('Spreadsheet::Sheet','Spreadsheet')
+        sheet = self.doc.addObject('Spreadsheet::Sheet','Spreadsheet')
         sheet.set('B13',  '4')
         sheet.set('B14',  '5')
         sheet.set('B15',  '6')
@@ -436,6 +437,25 @@ class SpreadsheetCases(unittest.TestCase):
         sheet.set('A38', '=(2^2*2)/8')
         sheet.set('A39', '=2^(2*2)/8')
         sheet.set('A40', '=8/2^(2*2)')
+        sheet.set('A41', '=-1')
+        sheet.set('A42', '=-(1)')
+        sheet.set('A43', '=-(1 + 1)')
+        sheet.set('A44', '=-(1 - 1)')
+        sheet.set('A45', '=-(-1 + 1)')
+        sheet.set('A46', '=-(-1 + -1)')
+        sheet.set('A47', '=+1')
+        sheet.set('A48', '=+(1)')
+        sheet.set('A49', '=+(1 + 1)')
+        sheet.set('A50', '=+(1 - 1)')
+        sheet.set('A51', '=+(-1 + 1)')
+        sheet.set('A52', '=+(-1 + -1)')
+
+        self.doc.addObject("Part::Cylinder", "Cylinder")
+        self.doc.addObject("Part::Thickness", "Pipe")
+        sheet.set('B1', '101')
+        sheet.set('A53', '=-(-(B1-1)/2)')
+        sheet.set('A54', '=-(Cylinder.Radius + Pipe.Value*1mm - 1"/2)')
+
         self.doc.recompute()
         self.assertEqual(sheet.getContents("A1"), "=1 < 2 ? 3 : 4")
         self.assertEqual(sheet.getContents("A2"), "=1 + 2 < 3 + 4 ? 5 + 6 : 7 + 8")
@@ -475,6 +495,20 @@ class SpreadsheetCases(unittest.TestCase):
         self.assertEqual(sheet.A38, 1)
         self.assertEqual(sheet.A39, 2)
         self.assertEqual(sheet.A40, 0.5)
+        self.assertEqual(sheet.A41, -1)
+        self.assertEqual(sheet.A42, -1)
+        self.assertEqual(sheet.A43, -2)
+        self.assertEqual(sheet.A44, 0)
+        self.assertEqual(sheet.A45, 0)
+        self.assertEqual(sheet.A46, 2)
+        self.assertEqual(sheet.A47, 1)
+        self.assertEqual(sheet.A48, 1)
+        self.assertEqual(sheet.A49, 2)
+        self.assertEqual(sheet.A50, 0)
+        self.assertEqual(sheet.A51, 0)
+        self.assertEqual(sheet.A52, -2)
+        self.assertEqual(sheet.A53, 50)
+        self.assertEqual(sheet.A54, Quantity('9.7mm'))
         self.assertEqual(sheet.getContents('A1'), '=1 < 2 ? 3 : 4')
         self.assertEqual(sheet.getContents('A2'), '=1 + 2 < 3 + 4 ? 5 + 6 : 7 + 8')
         self.assertEqual(sheet.getContents('A3'), '=1 + 2 * 1 < 3 + 4 ? 5 * 2 + 6 * 3 + 2 ^ 4 : 7 * 2 + 8 * 3 + 2 ^ 3')
@@ -515,6 +549,18 @@ class SpreadsheetCases(unittest.TestCase):
         self.assertEqual(sheet.getContents('A38'), '=2 ^ 2 * 2 / 8')
         self.assertEqual(sheet.getContents('A39'), '=2 ^ (2 * 2) / 8')
         self.assertEqual(sheet.getContents('A40'), '=8 / 2 ^ (2 * 2)')
+        self.assertEqual(sheet.getContents('A41'), '=-1')
+        self.assertEqual(sheet.getContents('A42'), '=-1')
+        self.assertEqual(sheet.getContents('A43'), '=-(1 + 1)')
+        self.assertEqual(sheet.getContents('A44'), '=-(1 - 1)')
+        self.assertEqual(sheet.getContents('A45'), '=-(-1 + 1)')
+        self.assertEqual(sheet.getContents('A46'), '=-(-1 + -1)')
+        self.assertEqual(sheet.getContents('A47'), '=+1')
+        self.assertEqual(sheet.getContents('A48'), '=+1')
+        self.assertEqual(sheet.getContents('A49'), '=+(1 + 1)')
+        self.assertEqual(sheet.getContents('A50'), '=+(1 - 1)')
+        self.assertEqual(sheet.getContents('A51'), '=+(-1 + 1)')
+        self.assertEqual(sheet.getContents('A52'), '=+(-1 + -1)')
 
     def testNumbers(self):
         """ Test different numbers """