diff --git a/src/libespeak-ng/sPlayer.h b/src/libespeak-ng/sPlayer.h
index 5d64e04d..4745ba7a 100644
--- a/src/libespeak-ng/sPlayer.h
+++ b/src/libespeak-ng/sPlayer.h
@@ -9,8 +9,8 @@
 extern "C" {
 #endif
 
-	void KlattInitSP();
-	void KlattResetSP();
+	void KlattInitSP(void);
+	void KlattResetSP(void);
 	int Wavegen_KlattSP(WGEN_DATA *wdata, voice_t *wvoice, int length, int resume, frame_t *fr1, frame_t *fr2);
 
 #ifdef __cplusplus