diff --git a/src/Airports/runways.hxx b/src/Airports/runways.hxx
index 204889d9e..4b6e5e3d1 100644
--- a/src/Airports/runways.hxx
+++ b/src/Airports/runways.hxx
@@ -36,7 +36,7 @@
 
 #include <simgear/compiler.h>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <istream>
 #elif defined( FG_HAVE_NATIVE_SGI_COMPILERS )
 #  include <iostream.h>
diff --git a/src/Airports/simple.hxx b/src/Airports/simple.hxx
index a3c757993..e4d371196 100644
--- a/src/Airports/simple.hxx
+++ b/src/Airports/simple.hxx
@@ -38,7 +38,7 @@
 
 #include <simgear/compiler.h>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <istream>
 #elif defined( FG_HAVE_NATIVE_SGI_COMPILERS )
 #  include <iostream.h>
diff --git a/src/FDM/JSBSim/FGAerodynamics.h b/src/FDM/JSBSim/FGAerodynamics.h
index 842eba5f4..cc29cb7e6 100644
--- a/src/FDM/JSBSim/FGAerodynamics.h
+++ b/src/FDM/JSBSim/FGAerodynamics.h
@@ -40,7 +40,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <vector>
 #  else
 #    include <vector.h>
diff --git a/src/FDM/JSBSim/FGAircraft.cpp b/src/FDM/JSBSim/FGAircraft.cpp
index 1c06fc673..566d324ec 100644
--- a/src/FDM/JSBSim/FGAircraft.cpp
+++ b/src/FDM/JSBSim/FGAircraft.cpp
@@ -109,7 +109,7 @@ INCLUDES
 #  ifndef __BORLANDC__
 #    include <simgear/compiler.h>
 #  endif
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <cmath>
 #  else
 #    include <math.h>
diff --git a/src/FDM/JSBSim/FGAircraft.h b/src/FDM/JSBSim/FGAircraft.h
index f1cb4c966..c1b22e590 100644
--- a/src/FDM/JSBSim/FGAircraft.h
+++ b/src/FDM/JSBSim/FGAircraft.h
@@ -40,7 +40,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <vector>
 #    include <iterator>
 #    include <map>
diff --git a/src/FDM/JSBSim/FGConfigFile.h b/src/FDM/JSBSim/FGConfigFile.h
index f9106a2ed..60e2d57e5 100644
--- a/src/FDM/JSBSim/FGConfigFile.h
+++ b/src/FDM/JSBSim/FGConfigFile.h
@@ -40,7 +40,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <fstream>
 #  else
 #    include <fstream.h>
diff --git a/src/FDM/JSBSim/FGEngine.cpp b/src/FDM/JSBSim/FGEngine.cpp
index a00b3c906..38b16a909 100644
--- a/src/FDM/JSBSim/FGEngine.cpp
+++ b/src/FDM/JSBSim/FGEngine.cpp
@@ -40,7 +40,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <fstream>
 #  else
 #    include <fstream.h>
diff --git a/src/FDM/JSBSim/FGFCS.h b/src/FDM/JSBSim/FGFCS.h
index 2ed40eb91..f09b12591 100644
--- a/src/FDM/JSBSim/FGFCS.h
+++ b/src/FDM/JSBSim/FGFCS.h
@@ -40,7 +40,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <vector>
 #  else
 #    include <vector.h>
diff --git a/src/FDM/JSBSim/FGFDMExec.cpp b/src/FDM/JSBSim/FGFDMExec.cpp
index 6e8964c49..caf4b9d14 100644
--- a/src/FDM/JSBSim/FGFDMExec.cpp
+++ b/src/FDM/JSBSim/FGFDMExec.cpp
@@ -40,7 +40,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <iostream>
 #    include <ctime>
 #  else
diff --git a/src/FDM/JSBSim/FGGroundReactions.h b/src/FDM/JSBSim/FGGroundReactions.h
index 5c4135ad3..8d53309ad 100644
--- a/src/FDM/JSBSim/FGGroundReactions.h
+++ b/src/FDM/JSBSim/FGGroundReactions.h
@@ -44,7 +44,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <vector>
 #  else
 #    include <vector.h>
diff --git a/src/FDM/JSBSim/FGInertial.h b/src/FDM/JSBSim/FGInertial.h
index b1a0b299b..d025b6e08 100644
--- a/src/FDM/JSBSim/FGInertial.h
+++ b/src/FDM/JSBSim/FGInertial.h
@@ -44,7 +44,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <vector>
 #  else
 #    include <vector.h>
diff --git a/src/FDM/JSBSim/FGMatrix.h b/src/FDM/JSBSim/FGMatrix.h
index 4e19f652a..1acb572e4 100644
--- a/src/FDM/JSBSim/FGMatrix.h
+++ b/src/FDM/JSBSim/FGMatrix.h
@@ -23,7 +23,7 @@ INCLUDES
 #include <stdlib.h>
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <fstream>
 #    include <cmath>
 #    include <iostream>
diff --git a/src/FDM/JSBSim/FGModel.h b/src/FDM/JSBSim/FGModel.h
index cfb00142e..9c8de946f 100644
--- a/src/FDM/JSBSim/FGModel.h
+++ b/src/FDM/JSBSim/FGModel.h
@@ -42,7 +42,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <iostream>
 #  else
 #    include <iostream.h>
diff --git a/src/FDM/JSBSim/FGOutput.h b/src/FDM/JSBSim/FGOutput.h
index 0e090f165..603fd77b2 100644
--- a/src/FDM/JSBSim/FGOutput.h
+++ b/src/FDM/JSBSim/FGOutput.h
@@ -42,7 +42,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <iostream>
 #    include <fstream>
 #  else
diff --git a/src/FDM/JSBSim/FGPosition.cpp b/src/FDM/JSBSim/FGPosition.cpp
index c10bb83ee..2a895b4c5 100644
--- a/src/FDM/JSBSim/FGPosition.cpp
+++ b/src/FDM/JSBSim/FGPosition.cpp
@@ -55,7 +55,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <cmath>
 #    include <iomanip>
 #  else
diff --git a/src/FDM/JSBSim/FGPropulsion.h b/src/FDM/JSBSim/FGPropulsion.h
index d4b260d19..c67c6a432 100644
--- a/src/FDM/JSBSim/FGPropulsion.h
+++ b/src/FDM/JSBSim/FGPropulsion.h
@@ -46,7 +46,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <vector>
 #  else
 #    include <vector.h>
diff --git a/src/FDM/JSBSim/FGRotation.h b/src/FDM/JSBSim/FGRotation.h
index deae5c7d5..b33f77642 100644
--- a/src/FDM/JSBSim/FGRotation.h
+++ b/src/FDM/JSBSim/FGRotation.h
@@ -58,7 +58,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <cmath>
 #  else
 #    include <math.h>
diff --git a/src/FDM/JSBSim/FGState.cpp b/src/FDM/JSBSim/FGState.cpp
index ce666ecbb..ec183c13c 100644
--- a/src/FDM/JSBSim/FGState.cpp
+++ b/src/FDM/JSBSim/FGState.cpp
@@ -38,7 +38,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <cmath>
 #  else
 #    include <math.h>
diff --git a/src/FDM/JSBSim/FGState.h b/src/FDM/JSBSim/FGState.h
index 119fb34b4..4e0fcf67f 100644
--- a/src/FDM/JSBSim/FGState.h
+++ b/src/FDM/JSBSim/FGState.h
@@ -46,7 +46,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <fstream>
 #  else
 #    include <fstream.h>
diff --git a/src/FDM/JSBSim/FGTranslation.h b/src/FDM/JSBSim/FGTranslation.h
index 1de210162..7eb04d6f4 100644
--- a/src/FDM/JSBSim/FGTranslation.h
+++ b/src/FDM/JSBSim/FGTranslation.h
@@ -58,7 +58,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <cmath>
 #  else
 #    include <math.h>
diff --git a/src/FDM/JSBSim/FGUtility.cpp b/src/FDM/JSBSim/FGUtility.cpp
index 50b13a015..b837060d8 100644
--- a/src/FDM/JSBSim/FGUtility.cpp
+++ b/src/FDM/JSBSim/FGUtility.cpp
@@ -44,7 +44,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <cmath>
 #  else
 #    include <math.h>
diff --git a/src/FDM/JSBSim/FGfdmSocket.h b/src/FDM/JSBSim/FGfdmSocket.h
index 0875c4355..f40429e83 100644
--- a/src/FDM/JSBSim/FGfdmSocket.h
+++ b/src/FDM/JSBSim/FGfdmSocket.h
@@ -47,7 +47,7 @@ INCLUDES
 #ifdef FGFS
 #  pragma message("FGFS defined")
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <iostream>
 #    include <fstream>
 #  else
diff --git a/src/FDM/JSBSim/JSBSim.cpp b/src/FDM/JSBSim/JSBSim.cpp
index 21bd12614..3d2c84d6a 100644
--- a/src/FDM/JSBSim/JSBSim.cpp
+++ b/src/FDM/JSBSim/JSBSim.cpp
@@ -105,7 +105,7 @@ USEUNIT("FGAerodynamics.cpp");
 #ifdef FGFS
 #include <simgear/compiler.h>
 #include STL_IOSTREAM
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <ctime>
 #  else
 #    include <time.h>
diff --git a/src/FDM/JSBSim/filtersjb/FGFlaps.h b/src/FDM/JSBSim/filtersjb/FGFlaps.h
index d26daaca6..ff71071d7 100644
--- a/src/FDM/JSBSim/filtersjb/FGFlaps.h
+++ b/src/FDM/JSBSim/filtersjb/FGFlaps.h
@@ -44,7 +44,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <vector>
 #  else
 #    include <vector.h>
diff --git a/src/FDM/JSBSim/filtersjb/FGGain.h b/src/FDM/JSBSim/filtersjb/FGGain.h
index 7e6f47bf7..d8efd9601 100644
--- a/src/FDM/JSBSim/filtersjb/FGGain.h
+++ b/src/FDM/JSBSim/filtersjb/FGGain.h
@@ -44,7 +44,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <vector>
 #  else
 #    include <vector.h>
diff --git a/src/FDM/JSBSim/filtersjb/FGSummer.h b/src/FDM/JSBSim/filtersjb/FGSummer.h
index 8872845b4..2ae397b34 100644
--- a/src/FDM/JSBSim/filtersjb/FGSummer.h
+++ b/src/FDM/JSBSim/filtersjb/FGSummer.h
@@ -44,7 +44,7 @@ INCLUDES
 
 #ifdef FGFS
 #  include <simgear/compiler.h>
-#  ifdef FG_HAVE_STD_INCLUDES
+#  ifdef SG_HAVE_STD_INCLUDES
 #    include <vector>
 #  else
 #    include <vector.h>
diff --git a/src/Navaids/fix.hxx b/src/Navaids/fix.hxx
index a70e3251f..0915cedb8 100644
--- a/src/Navaids/fix.hxx
+++ b/src/Navaids/fix.hxx
@@ -28,7 +28,7 @@
 #include <simgear/compiler.h>
 #include <simgear/misc/fgstream.hxx>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <istream>
 #elif defined( FG_HAVE_NATIVE_SGI_COMPILERS )
 #  include <iostream.h>
diff --git a/src/Navaids/ils.hxx b/src/Navaids/ils.hxx
index aada9a9aa..8fe322596 100644
--- a/src/Navaids/ils.hxx
+++ b/src/Navaids/ils.hxx
@@ -29,7 +29,7 @@
 #include <simgear/math/sg_geodesy.hxx>
 #include <simgear/misc/fgstream.hxx>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <istream>
 #elif defined( FG_HAVE_NATIVE_SGI_COMPILERS )
 #  include <iostream.h>
diff --git a/src/Navaids/nav.hxx b/src/Navaids/nav.hxx
index 97a7f2481..bdd83ca2e 100644
--- a/src/Navaids/nav.hxx
+++ b/src/Navaids/nav.hxx
@@ -32,7 +32,7 @@
 #include <simgear/magvar/magvar.hxx>
 #include <simgear/timing/sg_time.hxx>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <istream>
 #elif defined( FG_HAVE_NATIVE_SGI_COMPILERS )
 #  include <iostream.h>
diff --git a/src/Time/event.cxx b/src/Time/event.cxx
index 1282bafbe..c5cb4e61a 100644
--- a/src/Time/event.cxx
+++ b/src/Time/event.cxx
@@ -35,7 +35,7 @@
 #include STL_FUNCTIONAL
 #include STL_STRING
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <cstdio>
 #  ifdef HAVE_STDLIB_H
 #    include <cstdlib>
diff --git a/src/Time/light.cxx b/src/Time/light.cxx
index 5d3c45852..a7dcda076 100644
--- a/src/Time/light.cxx
+++ b/src/Time/light.cxx
@@ -39,7 +39,7 @@
 #  define exception c_exception
 #endif
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <cmath>
 #else
 #  include <math.h>
diff --git a/src/Time/moonpos.cxx b/src/Time/moonpos.cxx
index e1aebcf41..aa8d19228 100644
--- a/src/Time/moonpos.cxx
+++ b/src/Time/moonpos.cxx
@@ -42,7 +42,7 @@
 
 #include <simgear/compiler.h>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <cmath>
 #  include <cstdio>
 #  include <ctime>
diff --git a/src/Time/moonpos.hxx b/src/Time/moonpos.hxx
index 65e544ac2..50120350c 100644
--- a/src/Time/moonpos.hxx
+++ b/src/Time/moonpos.hxx
@@ -46,7 +46,7 @@
 
 #include <simgear/compiler.h>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <ctime>
 #  ifdef macintosh
      FG_USING_STD(time_t);
diff --git a/src/Time/sunpos.cxx b/src/Time/sunpos.cxx
index 896b0c531..945f8d396 100644
--- a/src/Time/sunpos.cxx
+++ b/src/Time/sunpos.cxx
@@ -40,7 +40,7 @@
 
 #include <simgear/compiler.h>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <cmath>
 #  include <cstdio>
 #  include <ctime>
diff --git a/src/Time/sunpos.hxx b/src/Time/sunpos.hxx
index 13bbd1845..7d38a9abf 100644
--- a/src/Time/sunpos.hxx
+++ b/src/Time/sunpos.hxx
@@ -46,7 +46,7 @@
 
 #include <simgear/compiler.h>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <ctime>
 #else
 #  include <time.h>
diff --git a/src/Weather/weather.hxx b/src/Weather/weather.hxx
index 73ec55002..e703d704b 100644
--- a/src/Weather/weather.hxx
+++ b/src/Weather/weather.hxx
@@ -29,7 +29,7 @@
 
 #include <simgear/xgl/xgl.h>
 
-#ifdef FG_HAVE_STD_INCLUDES
+#ifdef SG_HAVE_STD_INCLUDES
 #  include <cmath>
 #else
 #  include <math.h>