diff --git a/src/compr_quant_general.h b/src/compr_quant_general.h
new file mode 100644
index 000000000..b35311768
--- /dev/null
+++ b/src/compr_quant_general.h
@@ -0,0 +1,70 @@
+/*
+  Copyright 2010 SINTEF ICT, Applied Mathematics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_COMPR_QUANT_HEADER_INCLUDED
+#define OPM_COMPR_QUANT_HEADER_INCLUDED
+
+#include <stddef.h>
+
+#include "grid.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct compr_quantities {
+    int     nphases;      /* Number of phases/components */
+
+    double *Ac;           /* RB^{-1} per cell */
+    double *dAc;          /* d/dp (RB^{-1}) per cell */
+    double *Af;           /* RB^{-1} per face */
+    double *phasemobf;    /* Phase mobility per face */
+    double *voldiscr;     /* Volume discrepancy per cell */
+};
+
+struct compr_quantities *
+compr_quantities_allocate(size_t nc, size_t nf, int np);
+
+void
+compr_quantities_deallocate(struct compr_quantities *cq);
+
+void
+compr_flux_term(grid_t       *G,
+                const double *fflux,
+                const double *zeta,
+                double       *Biv);
+
+void
+compr_accum_term(size_t        nc,
+                 double        dt,
+                 const double *porevol,
+                 const double *totcompr,
+                 double       *P);
+
+void
+compr_src_add_press_accum(size_t        nc,
+                          const double *p0,
+                          const double *P,
+                          double       *src);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* OPM_COMPR_QUANT_HEADER_INCLUDED */