diff --git a/src/libespeak-ng/klatt.c b/src/libespeak-ng/klatt.c
index 0be73a75..78856f3a 100644
--- a/src/libespeak-ng/klatt.c
+++ b/src/libespeak-ng/klatt.c
@@ -937,7 +937,7 @@ int Wavegen_Klatt(int resume)
 	return 0;
 }
 
-void SetSynth_Klatt(int length, int modn, frame_t *fr1, frame_t *fr2, voice_t *v, int control)
+void SetSynth_Klatt(int length, frame_t *fr1, frame_t *fr2, voice_t *v, int control)
 {
 	int ix;
 	DOUBLEX next;
@@ -1053,10 +1053,10 @@ void SetSynth_Klatt(int length, int modn, frame_t *fr1, frame_t *fr2, voice_t *v
 	}
 }
 
-int Wavegen_Klatt2(int length, int modulation, int resume, frame_t *fr1, frame_t *fr2)
+int Wavegen_Klatt2(int length, int resume, frame_t *fr1, frame_t *fr2)
 {
 	if (resume == 0)
-		SetSynth_Klatt(length, modulation, fr1, fr2, wvoice, 1);
+		SetSynth_Klatt(length, fr1, fr2, wvoice, 1);
 
 	return Wavegen_Klatt(resume);
 }
diff --git a/src/libespeak-ng/synthesize.h b/src/libespeak-ng/synthesize.h
index ac8816bf..32d06f8c 100644
--- a/src/libespeak-ng/synthesize.h
+++ b/src/libespeak-ng/synthesize.h
@@ -562,7 +562,7 @@ void InitBreath(void);
 
 void KlattInit();
 void KlattReset(int control);
-int Wavegen_Klatt2(int length, int modulation, int resume, frame_t *fr1, frame_t *fr2);
+int Wavegen_Klatt2(int length, int resume, frame_t *fr1, frame_t *fr2);
 
 #ifdef __cplusplus
 }
diff --git a/src/libespeak-ng/wavegen.c b/src/libespeak-ng/wavegen.c
index 11da802c..f3481461 100644
--- a/src/libespeak-ng/wavegen.c
+++ b/src/libespeak-ng/wavegen.c
@@ -1606,7 +1606,7 @@ int WavegenFill2()
 			wdata.n_mix_wavefile = 0; // ... and drop through to WCMD_SPECT case
 		case WCMD_KLATT:
 			echo_complete = echo_length;
-			result = Wavegen_Klatt2(length & 0xffff, q[1] >> 16, resume, (frame_t *)q[2], (frame_t *)q[3]);
+			result = Wavegen_Klatt2(length & 0xffff, resume, (frame_t *)q[2], (frame_t *)q[3]);
 			break;
 #endif
 		case WCMD_MARKER: