diff --git a/fobos b/fobos
index 86bac5f1..aa886fc2 100644
--- a/fobos
+++ b/fobos
@@ -9,12 +9,12 @@ modes = shared-gnu static-gnu shared-gnu-debug static-gnu-debug
         test-driver-string-gnu-coverage
 
 [common-variables]
-$CSHARED_GNU = -DGNU -cpp -c -fPIC -frealloc-lhs
+$CSHARED_GNU = -cpp -c -fPIC -frealloc-lhs
 $CSHARED_INT = -cpp -c -fpic -assume realloc_lhs
 $LSHARED     = -shared
-$CSTATIC_GNU = -DGNU -cpp -c -frealloc-lhs
+$CSTATIC_GNU = -cpp -c -frealloc-lhs
 $CSTATIC_INT = -cpp -c -assume realloc_lhs
-$DEBUG_GNU   = -DGNU -O0 -g3 -Warray-bounds -Wcharacter-truncation -Wline-truncation -Wimplicit-interface -Wimplicit-procedure -Wunderflow -fcheck=all -fmodule-private -ffree-line-length-132 -fimplicit-none -fbacktrace -fdump-core -finit-real=nan -std=f2008 -fall-intrinsics
+$DEBUG_GNU   = -O0 -g3 -Warray-bounds -Wcharacter-truncation -Wline-truncation -Wimplicit-interface -Wimplicit-procedure -Wunderflow -fcheck=all -fmodule-private -ffree-line-length-132 -fimplicit-none -fbacktrace -fdump-core -finit-real=nan -std=f2008 -fall-intrinsics
 $DEBUG_INT   = -O0 -debug all -check all -warn all -extend-source 132 -traceback -gen-interfaces#-fpe-all=0 -fp-stack-check -fstack-protector-all -ftrapuv -no-ftz -std08
 $OPTIMIZE    = -O2
 
diff --git a/makefile b/makefile
index 861cc27b..3ad3055c 100644
--- a/makefile
+++ b/makefile
@@ -7,7 +7,7 @@ DMOD    = Test_Driver/mod/
 DEXE    = Test_Driver/
 LIBS    =
 FC      = gfortran
-OPTSC   =  -DGNU -cpp -c -frealloc-lhs -O2  -J Test_Driver/mod/
+OPTSC   =  -cpp -c -frealloc-lhs -O2  -J Test_Driver/mod/
 OPTSL   =  -J Test_Driver/mod/
 VPATH   = $(DSRC) $(DOBJ) $(DMOD)
 MKDIRS  = $(DOBJ) $(DMOD) $(DEXE)
diff --git a/src/Data_Type_Command_Line_Interface.F90 b/src/Data_Type_Command_Line_Interface.F90
index 1135bcdb..9b6c834c 100644
--- a/src/Data_Type_Command_Line_Interface.F90
+++ b/src/Data_Type_Command_Line_Interface.F90
@@ -100,7 +100,7 @@ module Data_Type_Command_Line_Interface
   !< Command Line Interface (CLI).
   private
   type(Type_Command_Line_Arguments_Group), allocatable:: clasg(:)            !< CLA list [1:Na].
-#ifdef GNU
+#ifdef __GFORTRAN__
   character(100  ), allocatable::                        args(:)             !< Actually passed command line arguments.
   character(100  ), allocatable::                        examples(:)         !< Examples of correct usage.
 #else
@@ -1513,7 +1513,7 @@ pure subroutine init(cli,progname,version,help,description,license,authors,examp
   cli%epilog      = ''        ; if (present(epilog     )) cli%epilog      = epilog
   if (present(disable_hv)) cli%disable_hv = .true.
   if (present(examples)) then
-#ifdef GNU
+#ifdef __GFORTRAN__
     allocate(cli%examples(1:size(examples)))
 #else
     allocate(character(len=len(examples(1))):: cli%examples(1:size(examples))) ! does not work with gfortran 4.9.2
@@ -1989,7 +1989,7 @@ subroutine get_args_from_string(cli,args,ai)
   integer(I4P)::                                      a      !< Counter for CLAs.
   integer(I4P)::                                      t      !< Counter for tokens.
   integer(I4P)::                                      c      !< Counter for characters inside tokens.
-#ifndef GNU
+#ifndef __GFORTRAN__
   integer(I4P)::                                      length !< Maxium lenght of arguments string.
 #endif
   !---------------------------------------------------------------------------------------------------------------------------------
@@ -2020,7 +2020,7 @@ subroutine get_args_from_string(cli,args,ai)
 
   if (Na > 0) then
     ! allocate cli arguments list
-#ifdef GNU
+#ifdef __GFORTRAN__
     allocate(cli%args(1:Na))
 #else
     length = 0
@@ -2097,7 +2097,7 @@ subroutine get_args_from_invocation(cli,ai)
   if (allocated(cli%args)) deallocate(cli%args)
   Na = command_argument_count()
   if (Na > 0) then
-#ifdef GNU
+#ifdef __GFORTRAN__
     allocate(cli%args(1:Na))
 #else
     aa = 0