diff --git a/newlib/ChangeLog b/newlib/ChangeLog
index d1ae16fa1..574ae506f 100644
--- a/newlib/ChangeLog
+++ b/newlib/ChangeLog
@@ -1,3 +1,11 @@
+2010-12-02  Craig Howland <howland@LGSInnovations.com>
+
+	* libm/common/s_log2.c:  Change from using M_LOG2_E to M_LN2 define
+	(from math.h--the latter is POSIX, the former non-standard).
+	* libm/common/sf_log2.c:  Ditto.  Change cast for M_LN2 from float to
+	float_t (in case all math not done in float).
+	* libc/include/math.h:  Ditto (same 2 things as sf_log2.c).
+
 2010-12-02  Jayant Sonar  jayant.sonar@kpitcummins.com
 	    Kaushik Phatak  kaushik.phatak@kpitcummins.com
 
diff --git a/newlib/libm/common/s_log2.c b/newlib/libm/common/s_log2.c
index 7ad2cd88b..e5087858b 100644
--- a/newlib/libm/common/s_log2.c
+++ b/newlib/libm/common/s_log2.c
@@ -34,8 +34,8 @@ The Newlib implementations are not full, intrinisic calculations, but
 rather are derivatives based on <<log>>.  (Accuracy might be slightly off from
 a direct calculation.)  In addition to functions, they are also implemented as
 macros defined in math.h:
-. #define log2(x) (log (x) / _M_LOG2_E)
-. #define log2f(x) (logf (x) / (float) _M_LOG2_E)
+. #define log2(x) (log (x) / _M_LN2)
+. #define log2f(x) (logf (x) / (float) _M_LN2)
 To use the functions instead, just undefine the macros first.
 
 You can use the (non-ANSI) function <<matherr>> to specify error
@@ -79,7 +79,7 @@ C99, POSIX, System V Interface Definition (Issue 6).
 	double x;
 #endif
 {
-  return (log(x) / M_LOG2_E);
+  return (log(x) / M_LN2);
 }
 
 #endif /* defined(_DOUBLE_IS_32BITS) */
diff --git a/newlib/libm/common/sf_log2.c b/newlib/libm/common/sf_log2.c
index eb8863c9f..9fbaaca72 100644
--- a/newlib/libm/common/sf_log2.c
+++ b/newlib/libm/common/sf_log2.c
@@ -30,7 +30,7 @@
 	float x;
 #endif
 {
-  return (logf(x) / (float) M_LOG2_E);
+  return (logf(x) / (float_t) M_LN2);
 }
 
 #ifdef _DOUBLE_IS_32BITS