diff --git a/core/vb.c b/core/vb.c
index 242e66e..ef0790b 100644
--- a/core/vb.c
+++ b/core/vb.c
@@ -664,9 +664,9 @@ VBAPI vbOnRead vbSetReadCallback(VB *sim, vbOnRead callback) {
 
 /* Specify a new audio samples buffer */
 VBAPI int vbSetSamples(VB *sim, void *samples, uint32_t capacity) {
-    if (capacity == 0 || capacity > 0x40000000)
+    if (samples != NULL && (capacity == 0 || capacity > 0x40000000))
         return 1;
-    sim->vsu.out.capacity = capacity;
+    sim->vsu.out.capacity = samples == NULL ? 0 : capacity;
     sim->vsu.out.offset   = 0;
     sim->vsu.out.samples  = samples;
     return 0;