diff --git a/src/vrend_decode.c b/src/vrend_decode.c
index 06e2fb6..bc0cc1b 100644
--- a/src/vrend_decode.c
+++ b/src/vrend_decode.c
@@ -283,19 +283,18 @@ static int vrend_decode_set_index_buffer(struct vrend_context *ctx, const uint32
 static int vrend_decode_set_constant_buffer(struct vrend_context *ctx, const uint32_t *buf, uint32_t length)
 {
    uint32_t shader;
-   uint32_t index;
    int nc = (length - 2);
 
    if (length < 2)
       return EINVAL;
 
    shader = get_buf_entry(buf, VIRGL_SET_CONSTANT_BUFFER_SHADER_TYPE);
-   index = get_buf_entry(buf, VIRGL_SET_CONSTANT_BUFFER_INDEX);
+   /* VIRGL_SET_CONSTANT_BUFFER_INDEX is not used */
 
    if (shader >= PIPE_SHADER_TYPES)
       return EINVAL;
 
-   vrend_set_constants(ctx, shader, index, nc, get_buf_ptr(buf, VIRGL_SET_CONSTANT_BUFFER_DATA_START));
+   vrend_set_constants(ctx, shader, nc, get_buf_ptr(buf, VIRGL_SET_CONSTANT_BUFFER_DATA_START));
    return 0;
 }
 
diff --git a/src/vrend_renderer.c b/src/vrend_renderer.c
index ec7f360..632c3c6 100644
--- a/src/vrend_renderer.c
+++ b/src/vrend_renderer.c
@@ -2714,7 +2714,6 @@ void vrend_bind_vertex_elements_state(struct vrend_context *ctx,
 
 void vrend_set_constants(struct vrend_context *ctx,
                          uint32_t shader,
-                         UNUSED uint32_t index,
                          uint32_t num_constant,
                          const float *data)
 {
diff --git a/src/vrend_renderer.h b/src/vrend_renderer.h
index ba4bc54..639caaf 100644
--- a/src/vrend_renderer.h
+++ b/src/vrend_renderer.h
@@ -327,7 +327,6 @@ void vrend_set_min_samples(struct vrend_context *ctx, unsigned min_samples);
 
 void vrend_set_constants(struct vrend_context *ctx,
                          uint32_t shader,
-                         uint32_t index,
                          uint32_t num_constant,
                          const float *data);