diff --git a/backends/midi/camd.cpp b/backends/midi/camd.cpp
index 9909cb00cf3..cc791cf7c06 100644
--- a/backends/midi/camd.cpp
+++ b/backends/midi/camd.cpp
@@ -137,8 +137,8 @@ void MidiDriver_CAMD::sysEx(const byte *msg, uint16 length) {
 char *MidiDriver_CAMD::getDevice() {
 	char *retname = NULL;
 
-	APTR key;
-	if (key = _ICamd->LockCAMD(CD_Linkages)) {
+	APTR key = _ICamd->LockCAMD(CD_Linkages);
+	if (key != NULL) {
 		struct MidiCluster *cluster = _ICamd->NextCluster(NULL);
 
 		while (cluster && !retname) {