diff --git a/src/libespeak-ng/phoneme.h b/src/libespeak-ng/phoneme.h
index 305fcba6..e6ed1fc6 100644
--- a/src/libespeak-ng/phoneme.h
+++ b/src/libespeak-ng/phoneme.h
@@ -281,8 +281,6 @@ typedef struct {
 #define PH3(c1, c2, c3) (c3<<16)+(c2<<8)+c1
 #define PhonemeCode2(c1, c2) PhonemeCode((c2<<8)+c1)
 
-extern const char *WordToString(unsigned int word);
-
 extern PHONEME_TAB_LIST phoneme_tab_list[N_PHONEME_TABS];
 extern int phoneme_tab_number;
 
diff --git a/src/libespeak-ng/synthesize.h b/src/libespeak-ng/synthesize.h
index ef99b371..bbddfbff 100644
--- a/src/libespeak-ng/synthesize.h
+++ b/src/libespeak-ng/synthesize.h
@@ -493,6 +493,7 @@ void DoPhonemeMarker(int type, int char_posn, int length, char *name);
 int DoSample3(PHONEME_DATA *phdata, int length_mod, int amp);
 int DoSpect2(PHONEME_TAB *this_ph, int which, FMT_PARAMS *fmt_params,  PHONEME_LIST *plist, int modulation);
 int PauseLength(int pause, int control);
+const char *WordToString(unsigned int word);
 
 #ifdef __cplusplus
 }