diff --git a/src/FDM/JSBSim/FGAircraft.cpp b/src/FDM/JSBSim/FGAircraft.cpp
index bdcd53c4b..18be53e26 100644
--- a/src/FDM/JSBSim/FGAircraft.cpp
+++ b/src/FDM/JSBSim/FGAircraft.cpp
@@ -168,7 +168,7 @@ bool FGAircraft::LoadAircraft(string aircraft_path, string engine_path, string f
   while (!aircraftfile.fail()) {
   	holding_string.erase();
     aircraftfile >> holding_string;
-#if defined(__BORLANDC__) || defined(FG_HAVE_NATIVE_SGI_COMPILERS)
+#if defined(__BORLANDC__) || defined(FG_HAVE_NATIVE_SGI_COMPILERS) || defined(_MSC_VER)
     if (holding_string.compare(0, 2, "//") != 0) {
 #else
     if (holding_string.compare("//",0,2) != 0) {
diff --git a/src/FDM/JSBSim/FGRotation.cpp b/src/FDM/JSBSim/FGRotation.cpp
index 494d9da66..43712681c 100644
--- a/src/FDM/JSBSim/FGRotation.cpp
+++ b/src/FDM/JSBSim/FGRotation.cpp
@@ -66,6 +66,12 @@ INCLUDES
 #include "FGAuxiliary.h"
 #include "FGOutput.h"
 
+#ifndef M_PI
+/* get a definition for pi */
+#include <Include/fg_constants.h>
+#define M_PI FG_PI
+#endif
+
 /*******************************************************************************
 ************************************ CODE **************************************
 *******************************************************************************/
diff --git a/src/FDM/JSBSim/FGUtility.cpp b/src/FDM/JSBSim/FGUtility.cpp
index 4d18883db..0d672d56d 100644
--- a/src/FDM/JSBSim/FGUtility.cpp
+++ b/src/FDM/JSBSim/FGUtility.cpp
@@ -57,6 +57,12 @@ INCLUDES
 #include "FGState.h"
 #include "FGFDMExec.h"
 
+#ifndef M_PI
+/* get a definition for pi */
+#include <Include/fg_constants.h>
+#define M_PI FG_PI
+#endif
+
 /*******************************************************************************
 ************************************ CODE **************************************
 *******************************************************************************/