diff --git a/audio/filter/af_scaletempo.c b/audio/filter/af_scaletempo.c
index 060a5b08a902c..f37e9b7d5a5ef 100644
--- a/audio/filter/af_scaletempo.c
+++ b/audio/filter/af_scaletempo.c
@@ -389,9 +389,10 @@ static void af_scaletempo_process(struct mp_filter *f)
         out_offset += s->bytes_stride;
 
         // input stride
-        memcpy(s->buf_overlap,
-               s->buf_queue + bytes_off + s->bytes_stride,
-               s->bytes_overlap);
+        if (s->buf_overlap && s->bytes_overlap)
+            memcpy(s->buf_overlap,
+                   s->buf_queue + bytes_off + s->bytes_stride,
+                   s->bytes_overlap);
         tf = s->frames_stride_scaled + s->frames_stride_error;
         ti = (int)tf;
         s->frames_stride_error = tf - ti;
diff --git a/video/out/vulkan/context.c b/video/out/vulkan/context.c
index 55584a07f9633..d062ea8028594 100644
--- a/video/out/vulkan/context.c
+++ b/video/out/vulkan/context.c
@@ -63,6 +63,11 @@ static inline OPT_STRING_VALIDATE_FUNC(vk_validate_dev)
         goto done;
 
     struct bstr param = bstr0(*value);
+    if (!param.len) {
+        mp_err(log, "No Vulkan device specified.\n");
+        ret = M_OPT_INVALID;
+        goto done;
+    }
     bool help = bstr_equals0(param, "help");
     if (help)
         mp_info(log, "Available vulkan devices:\n");