diff --git a/include/share/compat.h b/include/share/compat.h
index 022dc45b..6218b59b 100644
--- a/include/share/compat.h
+++ b/include/share/compat.h
@@ -174,6 +174,9 @@
 #define flac_fstat fstat
 #endif
 
+#ifndef M_LN2
+#define M_LN2 0.69314718055994530942
+#endif
 
 /* FLAC needs to compile and work correctly on systems with a norrmal ISO C99
  * snprintf as well as Microsoft Visual Studio which has an non-standards
diff --git a/src/libFLAC/fixed.c b/src/libFLAC/fixed.c
index 16b542d6..0995226c 100644
--- a/src/libFLAC/fixed.c
+++ b/src/libFLAC/fixed.c
@@ -36,15 +36,12 @@
 
 #include <math.h>
 #include <string.h>
+#include "share/compat.h"
 #include "private/bitmath.h"
 #include "private/fixed.h"
 #include "private/macros.h"
 #include "FLAC/assert.h"
 
-#ifndef M_LN2
-#define M_LN2 0.69314718055994530942
-#endif
-
 #ifdef local_abs
 #undef local_abs
 #endif
diff --git a/src/libFLAC/lpc.c b/src/libFLAC/lpc.c
index 476368ae..0fa54f89 100644
--- a/src/libFLAC/lpc.c
+++ b/src/libFLAC/lpc.c
@@ -51,10 +51,6 @@
 
 #ifndef FLAC__INTEGER_ONLY_LIBRARY
 
-#ifndef M_LN2
-#define M_LN2 0.69314718055994530942
-#endif
-
 #if !defined(HAVE_LROUND)
 #if defined(_MSC_VER)
 #include <float.h>