diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8a7e387a..0fe14c62 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,7 +10,7 @@ endif()
 if(CMAKE_CXX_COMPILER_ID STREQUAL "Intel")
   message("setting intel true")
   set(IntelComp true )
-elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU*")
+elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU*" OR CMAKE_CXX_COMPILER_ID MATCHES "Clang*")
   set(GNUComp true )
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "pgc*")
   set(PGIComp true )
@@ -28,9 +28,18 @@ if( (BUILD_RELEASE) OR (BUILD_PRODUCTION) )
     set(CMAKE_Fortran_8_FLAGS "-O3 -auto -qopenmp -i8 -r8 -convert big_endian -assume byterecl -fp-model strict -fpp -qopenmp -DLINUX " CACHE INTERNAL "" )
     set(CMAKE_Fortran_4_FLAGS "-O3 -auto -qopenmp -DLINUX -i4 -convert big_endian -assume byterecl -fp-model strict -real-size 32 -fpp -qopenmp" CACHE INTERNAL "" )
   elseif(GNUComp)
-  elseif(PGIComp)
+    message("setting gnu flags")
+    if (APPLE)
+      set(TMP_PLATFORM_FLAG "-DAPPLE")
+    elseif (UNIX)
+      set(TMP_PLATFORM_FLAG "-DLINUX")
+    endif()
+    set(CMAKE_Fortran_d_FLAGS "-O3 -fdefault-real-8 -fconvert=big-endian -cpp ${TMP_PLATFORM_FLAG} " CACHE INTERNAL "" )
+    set(CMAKE_Fortran_8_FLAGS "-O3 -fdefault-integer-8 -fdefault-real-8 -fconvert=big-endian -cpp ${TMP_PLATFORM_FLAG} " CACHE INTERNAL "" )
+    set(CMAKE_Fortran_4_FLAGS "-O3 -fconvert=big-endian -cpp ${TMP_PLATFORM_FLAG} " CACHE INTERNAL "" )
+    unset(TMP_PLATFORM_FLAG)
   else()
-    message("unkown compiler!")
+    message("unknown compiler!")
     exit()
   endif()
 endif()
diff --git a/src/fftpack.F b/src/fftpack.F
index afc1790c..775eb0ed 100644
--- a/src/fftpack.F
+++ b/src/fftpack.F
@@ -1,4 +1,4 @@
-#if LINUX 
+#if defined LINUX || defined APPLE
       SUBROUTINE dcrft(init,x,ldx,y,ldy,n,m,isign,scale,
      &                 table,n1,wrk,n2,z,nz)
  
diff --git a/src/ncpus.F b/src/ncpus.F
index 4ff8ee0d..698c290f 100644
--- a/src/ncpus.F
+++ b/src/ncpus.F
@@ -29,7 +29,7 @@ FUNCTION NCPUS()
 C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
       INTEGER NTHREADS, TID, OMP_GET_NUM_THREADS,OMP_GET_THREAD_NUM
 C     Obtain thread number
-#ifdef LINUX
+#if defined LINUX || defined APPLE
 !$OMP PARALLEL PRIVATE(TID)
       TID = OMP_GET_THREAD_NUM()
 !      PRINT *, '...............thread # ', TID