diff --git a/src/utils/fluid_conv.c b/src/utils/fluid_conv.c
index 13ea6b5e..ea4f0310 100644
--- a/src/utils/fluid_conv.c
+++ b/src/utils/fluid_conv.c
@@ -86,7 +86,7 @@ fluid_conversion_config(void)
      implemented according to the pictures on SF2.01 page 73. */
 
   for (i = 1; i < 127; i++) {
-    x = -20.0 / 96.0 * log((i * i) / (127.0 * 127.0)) / log(10.0);
+    x = -20.0 / 96.0 * log((i * i) / (127.0 * 127.0)) / M_LN10;
     fluid_convex_tab[i] = (fluid_real_t) (1.0 - x);
     fluid_concave_tab[127 - i] = (fluid_real_t) x;
   }
@@ -281,7 +281,7 @@ fluid_act2hz(fluid_real_t c)
 fluid_real_t
 fluid_hz2ct(fluid_real_t f)
 {
-  return (fluid_real_t) (6900 + 1200 * log(f / 440.0) / log(2.0));
+  return (fluid_real_t) (6900 + 1200 * log(f / 440.0) / M_LN2);
 }
 
 /*
diff --git a/src/utils/fluidsynth_priv.h b/src/utils/fluidsynth_priv.h
index 7289c413..ae134b74 100644
--- a/src/utils/fluidsynth_priv.h
+++ b/src/utils/fluidsynth_priv.h
@@ -206,10 +206,6 @@ typedef struct _fluid_sample_timer_t fluid_sample_timer_t;
 #define FLUID_DEFAULT_AUDIO_RT_PRIO  60         /**< Default setting for audio.realtime-prio */
 #define FLUID_DEFAULT_MIDI_RT_PRIO   50         /**< Default setting for midi.realtime-prio */
 
-#ifndef PI
-#define PI                          3.141592654
-#endif
-
 /***************************************************************
  *
  *                      SYSTEM INTERFACE
@@ -280,6 +276,13 @@ typedef FILE*  fluid_file;
 #define M_PI 3.1415926535897932384626433832795
 #endif
 
+#ifndef M_LN2
+#define M_LN2 0.69314718055994530941723212145818
+#endif
+
+#ifndef M_LN10
+#define M_LN10 2.3025850929940456840179914546844
+#endif
 
 #define FLUID_ASSERT(a,b)
 #define FLUID_ASSERT_P(a,b)