diff --git a/src/midi.c b/src/midi.c
index 7aebf27..62737fc 100644
--- a/src/midi.c
+++ b/src/midi.c
@@ -789,32 +789,32 @@ static void setFmChanParameter(DeviceChannel* devChan, u8 controller, u8 value)
         synth_operatorAttackRate(
             devChan->number, controller - CC_GENMDM_ATTACK_RATE_OP1, RANGE(value, 32));
         break;
-    case CC_GENMDM_FIRST_DECAY_RATE_OP1:
-    case CC_GENMDM_FIRST_DECAY_RATE_OP2:
-    case CC_GENMDM_FIRST_DECAY_RATE_OP3:
-    case CC_GENMDM_FIRST_DECAY_RATE_OP4:
+    case CC_GENMDM_DECAY_RATE_OP1:
+    case CC_GENMDM_DECAY_RATE_OP2:
+    case CC_GENMDM_DECAY_RATE_OP3:
+    case CC_GENMDM_DECAY_RATE_OP4:
         if (isIgnoringNonGeneralMidiCCs())
             break;
         synth_operatorDecayRate(
-            devChan->number, controller - CC_GENMDM_FIRST_DECAY_RATE_OP1, RANGE(value, 32));
+            devChan->number, controller - CC_GENMDM_DECAY_RATE_OP1, RANGE(value, 32));
         break;
-    case CC_GENMDM_SECOND_DECAY_RATE_OP1:
-    case CC_GENMDM_SECOND_DECAY_RATE_OP2:
-    case CC_GENMDM_SECOND_DECAY_RATE_OP3:
-    case CC_GENMDM_SECOND_DECAY_RATE_OP4:
+    case CC_GENMDM_SUSTAIN_RATE_OP1:
+    case CC_GENMDM_SUSTAIN_RATE_OP2:
+    case CC_GENMDM_SUSTAIN_RATE_OP3:
+    case CC_GENMDM_SUSTAIN_RATE_OP4:
         if (isIgnoringNonGeneralMidiCCs())
             break;
         synth_operatorSustainRate(
-            devChan->number, controller - CC_GENMDM_SECOND_DECAY_RATE_OP1, RANGE(value, 16));
+            devChan->number, controller - CC_GENMDM_SUSTAIN_RATE_OP1, RANGE(value, 16));
         break;
-    case CC_GENMDM_SECOND_AMPLITUDE_OP1:
-    case CC_GENMDM_SECOND_AMPLITUDE_OP2:
-    case CC_GENMDM_SECOND_AMPLITUDE_OP3:
-    case CC_GENMDM_SECOND_AMPLITUDE_OP4:
+    case CC_GENMDM_SUSTAIN_LEVEL_OP1:
+    case CC_GENMDM_SUSTAIN_LEVEL_OP2:
+    case CC_GENMDM_SUSTAIN_LEVEL_OP3:
+    case CC_GENMDM_SUSTAIN_LEVEL_OP4:
         if (isIgnoringNonGeneralMidiCCs())
             break;
         synth_operatorSustainLevel(
-            devChan->number, controller - CC_GENMDM_SECOND_AMPLITUDE_OP1, RANGE(value, 16));
+            devChan->number, controller - CC_GENMDM_SUSTAIN_LEVEL_OP1, RANGE(value, 16));
         break;
     case CC_GENMDM_RELEASE_RATE_OP1:
     case CC_GENMDM_RELEASE_RATE_OP2:
diff --git a/src/midi.h b/src/midi.h
index 675c827..762e0af 100644
--- a/src/midi.h
+++ b/src/midi.h
@@ -58,18 +58,18 @@
 #define CC_GENMDM_ATTACK_RATE_OP2 44
 #define CC_GENMDM_ATTACK_RATE_OP3 45
 #define CC_GENMDM_ATTACK_RATE_OP4 46
-#define CC_GENMDM_FIRST_DECAY_RATE_OP1 47
-#define CC_GENMDM_FIRST_DECAY_RATE_OP2 48
-#define CC_GENMDM_FIRST_DECAY_RATE_OP3 49
-#define CC_GENMDM_FIRST_DECAY_RATE_OP4 50
-#define CC_GENMDM_SECOND_DECAY_RATE_OP1 51
-#define CC_GENMDM_SECOND_DECAY_RATE_OP2 52
-#define CC_GENMDM_SECOND_DECAY_RATE_OP3 53
-#define CC_GENMDM_SECOND_DECAY_RATE_OP4 54
-#define CC_GENMDM_SECOND_AMPLITUDE_OP1 55
-#define CC_GENMDM_SECOND_AMPLITUDE_OP2 56
-#define CC_GENMDM_SECOND_AMPLITUDE_OP3 57
-#define CC_GENMDM_SECOND_AMPLITUDE_OP4 58
+#define CC_GENMDM_DECAY_RATE_OP1 47
+#define CC_GENMDM_DECAY_RATE_OP2 48
+#define CC_GENMDM_DECAY_RATE_OP3 49
+#define CC_GENMDM_DECAY_RATE_OP4 50
+#define CC_GENMDM_SUSTAIN_RATE_OP1 51
+#define CC_GENMDM_SUSTAIN_RATE_OP2 52
+#define CC_GENMDM_SUSTAIN_RATE_OP3 53
+#define CC_GENMDM_SUSTAIN_RATE_OP4 54
+#define CC_GENMDM_SUSTAIN_LEVEL_OP1 55
+#define CC_GENMDM_SUSTAIN_LEVEL_OP2 56
+#define CC_GENMDM_SUSTAIN_LEVEL_OP3 57
+#define CC_GENMDM_SUSTAIN_LEVEL_OP4 58
 #define CC_GENMDM_RELEASE_RATE_OP1 59
 #define CC_GENMDM_RELEASE_RATE_OP2 60
 #define CC_GENMDM_RELEASE_RATE_OP3 61
diff --git a/tests/unit/main.c b/tests/unit/main.c
index 54c34a0..277030f 100644
--- a/tests/unit/main.c
+++ b/tests/unit/main.c
@@ -131,9 +131,9 @@ int main(void)
         midi_test(test_midi_sets_operator_detune),
         midi_test(test_midi_sets_operator_rate_scaling),
         midi_test(test_midi_sets_operator_attack_rate),
-        midi_test(test_midi_sets_operator_first_decay_rate),
-        midi_test(test_midi_sets_operator_second_decay_rate),
-        midi_test(test_midi_sets_operator_secondary_amplitude),
+        midi_test(test_midi_sets_operator_decay_rate),
+        midi_test(test_midi_sets_operator_sustain_rate),
+        midi_test(test_midi_sets_operator_sustain_level),
         midi_test(test_midi_sets_operator_amplitude_modulation),
         midi_test(test_midi_sets_operator_release_rate),
         midi_test(test_midi_sets_operator_ssg_eg),
@@ -218,11 +218,11 @@ int main(void)
         synth_test(test_synth_sets_feedback_and_algorithm),
         synth_test(test_synth_sets_operator_multiple_and_detune),
         synth_test(test_synth_sets_operator_attack_rate_and_rate_scaling),
-        synth_test(test_synth_sets_operator_second_decay_rate),
+        synth_test(test_synth_sets_operator_sustain_rate),
         synth_test(
-            test_synth_sets_operator_release_rate_and_secondary_amplitude),
+            test_synth_sets_operator_release_rate_and_sustain_level),
         synth_test(
-            test_synth_sets_operator_amplitude_modulation_and_first_decay_rate),
+            test_synth_sets_operator_amplitude_modulation_and_decay_rate),
         synth_test(test_synth_sets_operator_ssg_eg),
         synth_test(test_synth_sets_global_LFO_enable_and_frequency),
         synth_test(test_synth_sets_busy_indicators),
diff --git a/tests/unit/test_midi_fm.c b/tests/unit/test_midi_fm.c
index 8042257..938639d 100644
--- a/tests/unit/test_midi_fm.c
+++ b/tests/unit/test_midi_fm.c
@@ -275,7 +275,7 @@ static void test_midi_sets_operator_attack_rate(UNUSED void** state)
     }
 }
 
-static void test_midi_sets_operator_first_decay_rate(UNUSED void** state)
+static void test_midi_sets_operator_decay_rate(UNUSED void** state)
 {
     const u8 expectedValue = 2;
     for (u8 chan = 0; chan < MAX_FM_CHANS; chan++) {
@@ -290,7 +290,7 @@ static void test_midi_sets_operator_first_decay_rate(UNUSED void** state)
     }
 }
 
-static void test_midi_sets_operator_second_decay_rate(UNUSED void** state)
+static void test_midi_sets_operator_sustain_rate(UNUSED void** state)
 {
     const u8 expectedValue = 1;
 
@@ -306,7 +306,7 @@ static void test_midi_sets_operator_second_decay_rate(UNUSED void** state)
     }
 }
 
-static void test_midi_sets_operator_secondary_amplitude(UNUSED void** state)
+static void test_midi_sets_operator_sustain_level(UNUSED void** state)
 {
     const u8 expectedValue = 1;
 
diff --git a/tests/unit/test_synth.c b/tests/unit/test_synth.c
index 71d8a9a..62523f1 100644
--- a/tests/unit/test_synth.c
+++ b/tests/unit/test_synth.c
@@ -201,7 +201,7 @@ static void test_synth_sets_operator_attack_rate_and_rate_scaling(UNUSED void**
     }
 }
 
-static void test_synth_sets_operator_second_decay_rate(UNUSED void** state)
+static void test_synth_sets_operator_sustain_rate(UNUSED void** state)
 {
     const u8 baseReg = 0x70;
     u8 sustainRate = 16;
@@ -213,7 +213,7 @@ static void test_synth_sets_operator_second_decay_rate(UNUSED void** state)
     }
 }
 
-static void test_synth_sets_operator_release_rate_and_secondary_amplitude(UNUSED void** state)
+static void test_synth_sets_operator_release_rate_and_sustain_level(UNUSED void** state)
 {
     const u8 baseReg = 0x80;
     u8 sustainLevel = 15;
@@ -228,7 +228,7 @@ static void test_synth_sets_operator_release_rate_and_secondary_amplitude(UNUSED
     }
 }
 
-static void test_synth_sets_operator_amplitude_modulation_and_first_decay_rate(UNUSED void** state)
+static void test_synth_sets_operator_amplitude_modulation_and_decay_rate(UNUSED void** state)
 {
     const u8 baseReg = 0x60;
     u8 amplitudeModulation = 1;