diff --git a/cmake/Modules/FindPetsc.cmake b/cmake/Modules/FindPETSc.cmake
similarity index 67%
rename from cmake/Modules/FindPetsc.cmake
rename to cmake/Modules/FindPETSc.cmake
index 9c6dd686..2bb6af2b 100644
--- a/cmake/Modules/FindPetsc.cmake
+++ b/cmake/Modules/FindPETSc.cmake
@@ -43,10 +43,9 @@ find_library(PETSC_BLAS_LIBRARY
 
 # print message if there was still no blas found!
 if(NOT BLAS_FOUND AND NOT PETSC_BLAS_LIBRARY)
-  message(STATUS "BLAS not found but required for PETSC")
+  message(STATUS "BLAS not found but required for PETSc")
   return()
 endif()
-list(APPEND CMAKE_REQUIRED_LIBRARIES "${PETSC_BLAS_LIBRARY}")
 
 set(PETSC_LAPACK_LIBRARY "")
 find_package(LAPACK QUIET)
@@ -62,62 +61,60 @@ find_library(PETSC_LAPACK_LIBRARY
 
 # print message if there was still no blas found!
 if(NOT LAPACK_FOUND AND NOT PETSC_LAPACK_LIBRARY)
-  message(STATUS "LAPACK not found but required for PETSC")
+  message(STATUS "LAPACK not found but required for PETSc")
   return()
 endif()
-list(APPEND CMAKE_REQUIRED_LIBRARIES "${PETSC_LAPACK_LIBRARY}")
 
 find_package(X11 QUIET)
 if (X11_FOUND)
     list(APPEND PETSC_X11_LIBRARY "${X11_LIBRARIES}")
 endif()
-list(APPEND CMAKE_REQUIRED_LIBRARIES "${PETSC_X11_LIBRARY}")
 
-# only probe if we haven't a path in our cache
-if (Petsc_ROOT)
- set (PETSC_ROOT "${Petsc_ROOT}")
-endif (Petsc_ROOT)
+# these variables must exist. Since not finding MPI, both the header and the
+# object file , may not be an error, we want the option of concatenating the
+# empty variable onto the PETSC_LIBRARIES/INCLUDE_DIRS lists
+set(PETSC_MPI_LIBRARY "")
+set(PETSC_MPI_INCLUDE_DIRS "")
 
-find_path (PETSC_NORMAL_INCLUDE_DIR
-    NAMES "petsc.h"
-    PATHS ${PETSC_ROOT}
-    PATH_SUFFIXES "petsc-3.4.4" "include" "petsc"
-    ${_no_default_path}
-    )
+find_package(MPI)
+if(MPI_FOUND)
+    list(APPEND PETSC_MPI_LIBRARY "${MPI_LIBRARIES}")
+    set(PETSC_MPI_INCLUDE_DIRS ${MPI_INCLUDE_PATH})
 
-# if parallel computing is explicitly enabled - reuse the paths and links from
-# OpmMainLib + OpmFind
-# this needs to be called explicitly as FindPetsc runs before OpmMainLib starts
-# looking for MPI (for some reason). Ideally this isn't necessary
-if(USE_MPI)
-    find_package(MPI)
-endif()
-
-set(PETSC_MPI_FOUND ${MPI_FOUND})
-set(PETSC_MPI_INCLUDE_DIRS ${MPI_INCLUDE_PATH})
-set(PETSC_MPI_LIBRARIES ${MPI_LIBRARIES})
-
-# fallback - use the petsc provided implementation of serial MPI.
-if (NOT PETSC_MPI_INCLUDE_DIRS)
-    message(STATUS "Building without MPI support - looking for PETSc provided serial implementation")
-    find_path (PETSC_MPI_INCLUDE_DIRS
+else(MPI_FOUND)
+# if a system MPI wasn't found, look for PETSc's serial implementation. This
+# won't be available if PETSc was compiled with --with-mpi=0, so not finding
+# this won't be an error. This only needs to find the header, as the MPI
+# implementation should be already be compiled into PETSc.
+    message(STATUS "Could not find a system provided MPI. Searching for PETSc provided mpiuni fallback implementation.")
+    find_path(PETSC_MPI_INCLUDE_DIRS
         NAMES "mpi.h"
         PATHS ${PETSC_ROOT}/include
         PATH_SUFFIXES "mpiuni"
         ${_no_default_path}
         )
+endif(MPI_FOUND)
 
-    if(PETSC_MPI_INCLUDE_DIRS)
-        set(PETSC_MPI_FOUND 1)
-    endif(PETSC_MPI_INCLUDE_DIRS)
-
+if(NOT PETSC_MPI_INCLUDE_DIRS)
+    message(WARNING "Could not find any MPI implementation. If PETSc is compiled with --with-mpi=0 this is ok. Otherwise you will get linker errors or (possibly subtle) runtime errors. Continuing.")
+    if(NOT USE_MPI)
+        message("To build with MPI support, pass -DUSE_MPI=ON to CMake.")
+    endif(NOT USE_MPI)
 endif(NOT PETSC_MPI_INCLUDE_DIRS)
 
-# couldn't find any usable mpi implementation - abort
-if(NOT PETSC_MPI_FOUND)
-    message(STATUS "Could not find any suitable MPI implementation.")
-    return()
-endif()
+# only probe if we haven't a path in our cache
+if (Petsc_ROOT)
+    set (PETSC_ROOT "${Petsc_ROOT}")
+endif (Petsc_ROOT)
+
+find_path (PETSC_NORMAL_INCLUDE_DIR
+    NAMES "petsc.h"
+    PATHS ${PETSC_ROOT}
+    PATH_SUFFIXES "include" "petsc"
+    ${_no_default_path}
+    )
+
+list(APPEND PETSC_INCLUDE_DIR ${PETSC_NORMAL_INCLUDE_DIR})
 
 # look for actual Petsc library
 find_library(PETSC_LIBRARY
@@ -132,11 +129,6 @@ if(NOT PETSC_LIBRARY)
   return()
 endif()
 
-list(APPEND CMAKE_REQUIRED_LIBRARIES "${PETSC_LIBRARY}" "${PETSC_MPI_LIBRARIES}")
-
-if (PETSC_MPI_INCLUDE_DIRS AND PETSC_NORMAL_INCLUDE_DIR)
-    list (APPEND PETSC_INCLUDE_DIR ${PETSC_MPI_INCLUDE_DIRS} ${PETSC_NORMAL_INCLUDE_DIR})
-endif()
 
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(Petsc DEFAULT_MSG PETSC_INCLUDE_DIR PETSC_LIBRARY)
@@ -145,9 +137,12 @@ mark_as_advanced(PETSC_INCLUDE_DIR PETSC_LIBRARY)
 # if both headers and library are found, store results
 if(PETSC_FOUND)
     set(PETSC_INCLUDE_DIRS ${PETSC_INCLUDE_DIR})
+    list(APPEND PETSC_INCLUDE_DIRS ${PETSC_MPI_INCLUDE_DIRS})
+
     set(PETSC_LIBRARIES ${PETSC_LIBRARY})
 
     list(APPEND PETSC_LIBRARIES ${PETSC_BLAS_LIBRARY})
     list(APPEND PETSC_LIBRARIES ${PETSC_LAPACK_LIBRARY})
     list(APPEND PETSC_LIBRARIES ${PETSC_X11_LIBRARY})
+    list(APPEND PETSC_LIBRARIES ${PETSC_MPI_LIBRARY})
 endif()
diff --git a/cmake/Modules/opm-core-prereqs.cmake b/cmake/Modules/opm-core-prereqs.cmake
index 8b5c29d4..ec118c58 100644
--- a/cmake/Modules/opm-core-prereqs.cmake
+++ b/cmake/Modules/opm-core-prereqs.cmake
@@ -26,13 +26,14 @@ set (opm-core_DEPS
 	"SuiteSparse COMPONENTS umfpack"
 	# solver
 	"SuperLU"
-	"Petsc"
 	# xml processing (for config parsing)
 	"TinyXML"
 	# Ensembles-based Reservoir Tools (ERT)
 	"ERT REQUIRED"
 	# Look for MPI support
 	"MPI"
+	# PETSc numerical backend
+	"PETSc"
 	# DUNE dependency
 	"dune-common"
 	"dune-istl"