diff --git a/ChangeLog b/ChangeLog
index a6d5eaf74fec6675c09f7666479a24cdcd1de072..35de5eb484bb3f98abfca20521bf00379dcf52a2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2010-04-24  Uwe Schulzweida  <Uwe.Schulzweida@zmaw.de>
+
+	* gaussgrid: define M_SQRT2 [report: alastair.mckinstry@ichec.ie]
+
 2010-04-16  Uwe Schulzweida  <Uwe.Schulzweida@zmaw.de>
 
 	* MAX_STREAMS: change static size of 4096 to dynamic range of 1024 - 65536
diff --git a/src/gaussgrid.c b/src/gaussgrid.c
index 10e2fd859011e29a6bedf79e3144f3a0cf40b1be..cf048a3db8a6238c315d0c401ff2a8f6707346d5 100644
--- a/src/gaussgrid.c
+++ b/src/gaussgrid.c
@@ -5,6 +5,12 @@
 
 #include "dmemory.h"
 
+
+#ifndef  M_SQRT2
+#define  M_SQRT2     1.41421356237309504880
+#endif
+
+
 static
 void cpledn(int kn, int kodd, double *pfn, double pdx, int kflag, 
             double *pw, double *pdxn, double *pxmod)