diff --git a/core/vb.c b/core/vb.c
index f5dc369..b37f2c1 100644
--- a/core/vb.c
+++ b/core/vb.c
@@ -361,8 +361,8 @@ struct VB {
 
             /* Other state */
             uint32_t clocks;   /* Clocks until modification */
-            uint8_t  modmask;  /* Modifications masked */
             uint8_t  freqmask; /* Frequency mask */
+            uint8_t  modmask;  /* Modifications masked */
             uint16_t next;     /* Next frequency value */
             int      sample;   /* Current sample index */
         } freqmod;
diff --git a/core/vsu.c b/core/vsu.c
index 3f52da9..6d129cd 100644
--- a/core/vsu.c
+++ b/core/vsu.c
@@ -82,11 +82,11 @@ static void vsuNextFreqMod(VB *sim, Channel *chan) {
 
     /* Modulation */
     else {
-        next = (int32_t) chan->freq.written +
-            sim->vsu.modulation[sim->vsu.freqmod.sample] & 0x7FF;
+        next = ((int32_t) chan->freq.written +
+            sim->vsu.modulation[sim->vsu.freqmod.sample]) & 0x7FF;
         if (sim->vsu.freqmod.freqmask == 1)
             next = (next & 0x700) | (chan->freq.written & 0x0FF);
-        else if (sim->vsu.freqmod.freqmask == 2) {
+        else if (sim->vsu.freqmod.freqmask == 2)
             next = (next & 0x0FF) | (chan->freq.written & 0x700);
     }
 
@@ -511,10 +511,10 @@ static void vsuReset(VB *sim) {
     sim->vsu.freqmod.clocks   = 0;
     sim->vsu.freqmod.dir      = 0;
     sim->vsu.freqmod.enb      = 0;
+    sim->vsu.freqmod.freqmask = 0;
     sim->vsu.freqmod.func     = 0;
     sim->vsu.freqmod.interval = 0;
     sim->vsu.freqmod.modmask  = 0;
-    sim->vsu.freqmod.freqmask = 0;
     sim->vsu.freqmod.next     = 0;
     sim->vsu.freqmod.rep      = 0;
     sim->vsu.freqmod.sample   = 0;