diff --git a/amgprec/amg_config.h.in b/amgprec/amg_config.h.in
index c2e3f2a3..f197a5f2 100644
--- a/amgprec/amg_config.h.in
+++ b/amgprec/amg_config.h.in
@@ -11,6 +11,7 @@
 @CHAVEMUMPS@
 @CHAVEMUMPSMODULES@
 @CHAVEMUMPSINCLUDES@
+@CXXMATCHBOXBIT@
 
 
 #endif
diff --git a/amgprec/impl/aggregator/MatchBoxPC.h b/amgprec/impl/aggregator/MatchBoxPC.h
index f412c64f..9cc0e89c 100644
--- a/amgprec/impl/aggregator/MatchBoxPC.h
+++ b/amgprec/impl/aggregator/MatchBoxPC.h
@@ -117,7 +117,7 @@ extern "C"
 // Regular long integer:
 #ifndef LONG_INT_H
 #define LONG_INT_H
-#ifdef BIT64
+#ifdef AMG_MATCHBOXP_BIT64
     typedef int64_t MilanLongInt;
     typedef MPI_LONG MilanMpiLongInt;
 #else
@@ -163,7 +163,7 @@ extern "C"
 #define MilanIntMax INT32_MAX
 #define MilanIntMin INT32_MIN
 
-#ifdef BIT64
+#ifdef AMG_MATCHBOXP_BIT64
 #define MilanLongIntMax INT64_MAX
 #define MilanLongIntMin -INT64_MAX
 #else
diff --git a/amgprec/impl/aggregator/primitiveDataTypeDefinitions.h b/amgprec/impl/aggregator/primitiveDataTypeDefinitions.h
index a8bc4d5b..0ee17590 100644
--- a/amgprec/impl/aggregator/primitiveDataTypeDefinitions.h
+++ b/amgprec/impl/aggregator/primitiveDataTypeDefinitions.h
@@ -49,8 +49,8 @@
 using namespace std;
 
 //Comment out these if you do not need 64 bits.
-//#ifndef BIT64
-//	#define BIT64
+//#ifndef AMG_MATCHBOXP_BIT64
+//	#define AMG_MATCHBOXP_BIT64
 //#endif
 
 //Regular integer:
@@ -63,7 +63,7 @@ using namespace std;
 //Regular long Integer:
 #ifndef LONG_INT_H
 #define LONG_INT_H
-	#ifdef BIT64
+	#ifdef AMG_MATCHBOXP_BIT64
 	typedef int64_t MilanLongInt;
 //	typedef MPI_LONG MilanMpiLongInt;
 	#else
@@ -108,7 +108,7 @@ using namespace std;
 #define MilanIntMax INT_MAX
 #define MilanIntMin INT_MIN
 
-#ifdef BIT64
+#ifdef AMG_MATCHBOXP_BIT64
 	#define MilanLongIntMax LONG_MAX
 	#define MilanLongIntMin -LONG_MAX
 #else
diff --git a/configure b/configure
index 0de54ec1..8387413a 100755
--- a/configure
+++ b/configure
@@ -667,6 +667,7 @@ SLU_FLAGS
 MUMPS_LIBS
 MUMPS_FLAGS
 EXTRA_LIBS
+CXXMATCHBOXBIT
 CHAVEMUMPSINCLUDES
 CHAVEMUMPSMODULES
 CHAVEMUMPS
@@ -7858,7 +7859,7 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: PSBLAS size of LPK \"$pac_cv_psblas_lpk\"." >&5
 printf "%s\n" "$as_me: PSBLAS size of LPK \"$pac_cv_psblas_lpk\"." >&6;}
 if test x"$pac_cv_psblas_lpk" == x8"" ; then
-  CXXDEFINES="$CXXDEFINES";
+   CXXMATCHBOXBIT="#define AMG_MATCHBOXP_BIT64"
 fi
 
 ###############################################################################
diff --git a/configure.ac b/configure.ac
index 3145b7c9..11fd8905 100755
--- a/configure.ac
+++ b/configure.ac
@@ -595,7 +595,7 @@ fi
 PAC_FORTRAN_PSBLAS_INTEGER_SIZES()
 AC_MSG_NOTICE([PSBLAS size of LPK "$pac_cv_psblas_lpk".])
 if test x"$pac_cv_psblas_lpk" == x8"" ; then
-  CXXDEFINES="$CXXDEFINES";
+   CXXMATCHBOXBIT="#define AMG_MATCHBOXP_BIT64"
 fi
 
 ###############################################################################
@@ -853,7 +853,7 @@ AC_SUBST(CSLUDISTVERSION)
 AC_SUBST(CHAVEMUMPS)
 AC_SUBST(CHAVEMUMPSMODULES)
 AC_SUBST(CHAVEMUMPSINCLUDES)
-
+AC_SUBST(CXXMATCHBOXBIT)
 
 
 AC_SUBST(EXTRA_LIBS)