diff --git a/src/libespeak-ng/speak_lib.c b/src/libespeak-ng/speak_lib.c
index 7483f8a2..c331fd4d 100644
--- a/src/libespeak-ng/speak_lib.c
+++ b/src/libespeak-ng/speak_lib.c
@@ -212,7 +212,7 @@ ESPEAK_NG_API espeak_ng_STATUS espeak_ng_InitializeOutput(espeak_ng_OUTPUT_MODE
 	option_waveout = 1; // inhibit portaudio callback from wavegen.cpp
 	out_samplerate = 0;
 
-	if (output_mode == ENOUTPUT_MODE_SYNCHRONOUS | ENOUTPUT_MODE_SPEAK_AUDIO) {
+	if (output_mode == (ENOUTPUT_MODE_SYNCHRONOUS | ENOUTPUT_MODE_SPEAK_AUDIO)) {
 		option_waveout = 0;
 		WavegenInitSound();
 	}