diff --git a/Makefile.am b/Makefile.am
index 7d172b38..9149e6dc 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -64,7 +64,6 @@ common_SOURCE = \
 	src/readclause.cpp \
 	src/phonemelist.cpp \
 	src/setlengths.cpp \
-	src/sonic.cpp \
 	src/synthdata.cpp \
 	src/synthesize.cpp \
 	src/synth_mbrola.cpp \
@@ -105,6 +104,11 @@ common_FLAGS  += -DINCLUDE_MBROLA
 common_SOURCE += src/mbrowrap.cpp
 endif
 
+if OPT_SONIC
+common_FLAGS  += -DINCLUDE_SONIC
+common_SOURCE += src/sonic.cpp
+endif
+
 if AUDIO_RUNTIME
 wave_SOURCE = src/wave.cpp src/wave_pulse.cpp
 wave_LIBS   = -lpulse -lpulse-simple -lportaudio
diff --git a/configure.ac b/configure.ac
index 3d7d0e93..ecbc08b9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -148,8 +148,19 @@ else
 	have_mbrola=yes
 fi
 
+AC_ARG_WITH([sonic],
+    [AS_HELP_STRING([--with-sonic], [enable the sonic library to speed up the audio @<:@default=yes@:>@])],
+    [])
+
+if test "$with_sonic" = "no" ; then
+	have_sonic=no
+else
+	have_sonic=yes
+fi
+
 AM_CONDITIONAL(OPT_KLATT,  [test x"$have_klatt"  = xyes])
 AM_CONDITIONAL(OPT_MBROLA, [test x"$have_mbrola" = xyes])
+AM_CONDITIONAL(OPT_SONIC,  [test x"$have_sonic"  = xyes])
 
 dnl ================================================================
 dnl wxWidgets checks.
@@ -191,4 +202,5 @@ AC_MSG_NOTICE([
 
 	Klatt:                         ${have_klatt}
 	MBROLA:                        ${have_mbrola}
+	Sonic:                         ${have_sonic}
 ])
diff --git a/src/sonic.cpp b/src/sonic.cpp
index 82febba5..99252d09 100644
--- a/src/sonic.cpp
+++ b/src/sonic.cpp
@@ -28,7 +28,6 @@
 
 #include "speech.h"
 #include "sonic.h"
-#ifdef INCLUDE_SONIC
 
 struct sonicStreamStruct {
     short *inputBuffer;
@@ -969,4 +968,3 @@ int sonicChangeShortSpeed(
     sonicDestroyStream(stream);
     return numSamples;
 }
-#endif  // INCLUDE_SONIC
diff --git a/src/speech.h b/src/speech.h
index 5cb82cac..60c045aa 100644
--- a/src/speech.h
+++ b/src/speech.h
@@ -23,9 +23,6 @@
 
 #include <sys/types.h>
 
-// conditional compilation options
-#define INCLUDE_SONIC
-
 #if defined(BYTE_ORDER) && BYTE_ORDER == BIG_ENDIAN
 #define ARCH_BIG
 #endif