diff --git a/src/cubeb_jack.cpp b/src/cubeb_jack.cpp
index b417078f..9d64b52c 100644
--- a/src/cubeb_jack.cpp
+++ b/src/cubeb_jack.cpp
@@ -405,12 +405,15 @@ cbjack_process(jack_nframes_t nframes, void * arg)
 
   for (int j = 0; j < MAX_STREAMS; j++) {
     cubeb_stream * stm = &ctx->streams[j];
-    float * bufs_out[stm->out_params.channels];
-    float * bufs_in[stm->in_params.channels];
 
     if (!stm->in_use)
       continue;
 
+    float * bufs_out[MAX_CHANNELS] = {};
+    float * bufs_in[MAX_CHANNELS] = {};
+    XASSERT(stm->out_params.channels <= MAX_CHANNELS);
+    XASSERT(stm->in_params.channels <= MAX_CHANNELS);
+
     // handle xruns by skipping audio that should have been played
     stm->position += t_jack_xruns * ctx->fragment_size * stm->ratio;
 
@@ -851,6 +854,14 @@ cbjack_stream_init(cubeb * context, cubeb_stream ** stream,
     return CUBEB_ERROR_INVALID_FORMAT;
   }
 
+  if ((output_stream_params &&
+       (output_stream_params->channels < 1 ||
+        output_stream_params->channels > MAX_CHANNELS)) ||
+      (input_stream_params && (input_stream_params->channels < 1 ||
+                               input_stream_params->channels > MAX_CHANNELS))) {
+    return CUBEB_ERROR_INVALID_FORMAT;
+  }
+
   if ((input_device && input_device != JACK_DEFAULT_IN) ||
       (output_device && output_device != JACK_DEFAULT_OUT)) {
     return CUBEB_ERROR_NOT_SUPPORTED;