diff --git a/poincare/include/poincare/matrix_data.h b/poincare/include/poincare/matrix_data.h
index f168aaf1b..53ef2fbe7 100644
--- a/poincare/include/poincare/matrix_data.h
+++ b/poincare/include/poincare/matrix_data.h
@@ -25,7 +25,6 @@ private:
   int m_numberOfRows;
   int m_numberOfColumns;
   const Expression ** m_operands;
-  static Complex<double> * defaultExpression();
 };
 
 }
diff --git a/poincare/src/expression_parser.y b/poincare/src/expression_parser.y
index 4c989fa9c..8218558e7 100644
--- a/poincare/src/expression_parser.y
+++ b/poincare/src/expression_parser.y
@@ -144,7 +144,7 @@ lstData:
 /* MATRICES_ARE_DEFINED */
  mtxData:
   LEFT_BRACKET lstData RIGHT_BRACKET { $$ = new Poincare::MatrixData($2, false); $2->detachOperands(); delete $2; }
-  | mtxData LEFT_BRACKET lstData RIGHT_BRACKET  { $$ = $1; $$->pushListData($3, false); $3->detachOperands(); delete $3; }
+  | mtxData LEFT_BRACKET lstData RIGHT_BRACKET  { if ($3->numberOfOperands() != $1->numberOfColumns()) { delete $1; delete $3; YYERROR; } ; $$ = $1; $$->pushListData($3, false); $3->detachOperands(); delete $3; }
 
 number:
   DIGITS { $$ = new Poincare::Rational(Poincare::Integer($1.address, false)); }
diff --git a/poincare/src/matrix_data.cpp b/poincare/src/matrix_data.cpp
index 8c1e31a3c..4ef93f708 100644
--- a/poincare/src/matrix_data.cpp
+++ b/poincare/src/matrix_data.cpp
@@ -23,10 +23,6 @@ MatrixData::MatrixData(ListData * listData, bool clone) :
   }
 }
 
-Complex<double> * MatrixData::defaultExpression() {
-  return new Complex<double>(Complex<double>::Float(0.0));
-}
-
 MatrixData::~MatrixData() {
   if (m_operands != nullptr) {
     for (int i=0; i<m_numberOfRows*m_numberOfColumns; i++) {
@@ -38,15 +34,15 @@ MatrixData::~MatrixData() {
 
 void MatrixData::pushListData(ListData * listData, bool clone) {
   const Expression ** newOperands = new const Expression * [(m_numberOfRows+1)*m_numberOfColumns];
+  assert(listData->numberOfOperands() == m_numberOfColumns);
   for (int i = 0; i < m_numberOfRows*m_numberOfColumns; i++) {
     newOperands[i] = m_operands[i];
   }
   for (int i = 0; i < m_numberOfColumns; i++) {
-    int max = listData->numberOfOperands();
     if (clone) {
-      newOperands[m_numberOfRows*m_numberOfColumns+i] = i < max ? listData->operand(i)->clone() : defaultExpression();
+      newOperands[m_numberOfRows*m_numberOfColumns+i] = listData->operand(i)->clone();
     } else {
-      newOperands[m_numberOfRows*m_numberOfColumns+i] = i < max ? listData->operand(i) : defaultExpression();
+      newOperands[m_numberOfRows*m_numberOfColumns+i] = listData->operand(i);
     }
   }
   delete[] m_operands;