diff --git a/dump.c b/dump.c
index 703f273..3c7c0ad 100644
--- a/dump.c
+++ b/dump.c
@@ -45,7 +45,7 @@ void emit(struct ovni_stream *stream, struct ovni_ev *ev)
 
 	printf("%d.%d.%d %c %c %c % 20ld % 15ld ",
 			stream->loom, stream->proc, stream->tid,
-			ev->header.model, ev->header.class, ev->header.value, clock, delta);
+			ev->header.model, ev->header.category, ev->header.value, clock, delta);
 
 	payloadsize = ovni_payload_size(ev);
 	for(i=0; i<payloadsize; i++)
diff --git a/emu.c b/emu.c
index 3660adc..90d1cf8 100644
--- a/emu.c
+++ b/emu.c
@@ -42,7 +42,7 @@ emit_ev(struct ovni_stream *stream, struct ovni_ev *ev)
 
 	dbg(">>> %d.%d.%d %c %c %c % 20ld % 15ld ",
 			stream->loom, stream->proc, stream->tid,
-			ev->header.model, ev->header.class, ev->header.value, clock, delta);
+			ev->header.model, ev->header.category, ev->header.value, clock, delta);
 
 	payloadsize = ovni_payload_size(ev);
 	for(i=0; i<payloadsize; i++)
@@ -776,7 +776,7 @@ emu_virtual_ev(struct ovni_emu *emu, char *mcv)
 
 	ev->header.flags = 0;
 	ev->header.model = mcv[0];
-	ev->header.class = mcv[1];
+	ev->header.category = mcv[1];
 	ev->header.value = mcv[2];
 	ev->header.clock = emu->cur_ev->header.clock;
 
diff --git a/emu_nosv.c b/emu_nosv.c
index 415b0d7..1fe9e88 100644
--- a/emu_nosv.c
+++ b/emu_nosv.c
@@ -422,7 +422,7 @@ hook_pre_nosv(struct ovni_emu *emu)
 {
 	assert(emu->cur_ev->header.model == 'V');
 
-	switch(emu->cur_ev->header.class)
+	switch(emu->cur_ev->header.category)
 	{
 		case 'T': pre_task(emu); break;
 		case 'Y': pre_type(emu); break;
diff --git a/emu_nosv_ss.c b/emu_nosv_ss.c
index e0714f0..05d8935 100644
--- a/emu_nosv_ss.c
+++ b/emu_nosv_ss.c
@@ -111,7 +111,7 @@ hook_pre_nosv_ss(struct ovni_emu *emu)
 {
 	assert(emu->cur_ev->header.model == 'V');
 
-	switch(emu->cur_ev->header.class)
+	switch(emu->cur_ev->header.category)
 	{
 		case 'S': pre_sched(emu); break;
 		case 'U': pre_submit(emu); break;
diff --git a/emu_ovni.c b/emu_ovni.c
index 3159665..3be97cd 100644
--- a/emu_ovni.c
+++ b/emu_ovni.c
@@ -549,14 +549,14 @@ hook_pre_ovni(struct ovni_emu *emu)
 	if(emu->cur_ev->header.model != 'O')
 		return;
 
-	switch(emu->cur_ev->header.class)
+	switch(emu->cur_ev->header.category)
 	{
 		case 'H': pre_thread(emu); break;
 		case 'A': pre_affinity(emu); break;
 		case 'B': pre_burst(emu); break;
 		default:
-			dbg("unknown ovni event class %c\n",
-					emu->cur_ev->header.class);
+			dbg("unknown ovni event category %c\n",
+					emu->cur_ev->header.category);
 			break;
 	}
 
diff --git a/ovni.c b/ovni.c
index b43d540..97df6ab 100644
--- a/ovni.c
+++ b/ovni.c
@@ -411,7 +411,7 @@ void
 ovni_ev_set_mcv(struct ovni_ev *ev, char *mcv)
 {
 	ev->header.model = mcv[0];
-	ev->header.class = mcv[1];
+	ev->header.category = mcv[1];
 	ev->header.value = mcv[2];
 }
 
diff --git a/ovni.h b/ovni.h
index 9f7cc1f..5992daa 100644
--- a/ovni.h
+++ b/ovni.h
@@ -51,7 +51,7 @@ struct __attribute__((__packed__)) ovni_ev_header {
 	/* first 4 bits reserved, last 4 for payload size */
 	uint8_t flags;
 	uint8_t model;
-	uint8_t class;
+	uint8_t category;
 	uint8_t value;
 	uint64_t clock;
 };
diff --git a/ovni2prv.c b/ovni2prv.c
index e74b758..ad29587 100644
--- a/ovni2prv.c
+++ b/ovni2prv.c
@@ -31,7 +31,7 @@ void emit(struct ovni_stream *stream, struct ovni_ev *ev, int row)
 	//2:0:1:1:7:1542091:6400025:1
 	//2:0:1:1:7:1542091:6400017:0
 
-	printf("2:0:1:1:%d:%ld:%d:%d\n", row, delta, ev->header.class, ev->header.value);
+	printf("2:0:1:1:%d:%ld:%d:%d\n", row, delta, ev->header.category, ev->header.value);
 }
 
 void dump_events(struct ovni_trace *trace)