diff --git a/Eigen/src/LU/FullPivLU.h b/Eigen/src/LU/FullPivLU.h
index fbb5a61bf..2b30fc146 100644
--- a/Eigen/src/LU/FullPivLU.h
+++ b/Eigen/src/LU/FullPivLU.h
@@ -436,7 +436,7 @@ template<typename _MatrixType> class FullPivLU
     Index m_nonzero_pivots;
     RealScalar m_l1_norm;
     RealScalar m_maxpivot, m_prescribedThreshold;
-    char m_det_pq;
+    signed char m_det_pq;
     bool m_isInitialized, m_usePrescribedThreshold;
 };
 
diff --git a/Eigen/src/LU/PartialPivLU.h b/Eigen/src/LU/PartialPivLU.h
index 6c35e88d3..d43961887 100644
--- a/Eigen/src/LU/PartialPivLU.h
+++ b/Eigen/src/LU/PartialPivLU.h
@@ -284,7 +284,7 @@ template<typename _MatrixType> class PartialPivLU
     PermutationType m_p;
     TranspositionType m_rowsTranspositions;
     RealScalar m_l1_norm;
-    char m_det_p;
+    signed char m_det_p;
     bool m_isInitialized;
 };