--- a/liboctave/SparseCmplxLU.cc
+++ b/liboctave/SparseCmplxLU.cc
@@ -37,14 +37,17 @@
 
 template class sparse_base_lu <SparseComplexMatrix, Complex, SparseMatrix, double>;
 
+#ifdef HAVE_UMFPACK
 // Include the UMFPACK functions
 extern "C" {
-#include "umfpack.h"
+#include <umfpack/umfpack.h>
 }
+#endif
 
 SparseComplexLU::SparseComplexLU (const SparseComplexMatrix& a, 
 				  double piv_thres)
 {
+#ifdef HAVE_UMFPACK
   int nr = a.rows ();
   int nc = a.cols ();
 
@@ -210,12 +213,16 @@
 	    }
 	}
     }
+#else
+  (*current_liboctave_error_handler) ("UMFPACK not installed");
+#endif
 }
 
 SparseComplexLU::SparseComplexLU (const SparseComplexMatrix& a, 
 				  const ColumnVector& Qinit, 
 				  double piv_thres, bool FixedQ)
 {
+#ifdef HAVE_UMFPACK
   int nr = a.rows ();
   int nc = a.cols ();
 
@@ -395,6 +402,9 @@
 	    }
 	}
     }
+#else
+  (*current_liboctave_error_handler) ("UMFPACK not installed");
+#endif
 }
 
 /*