diff --git a/libavfilter/vf_frei0r.c b/libavfilter/vf_frei0r.c
index 8602d3fc81..5ace481238 100644
--- a/libavfilter/vf_frei0r.c
+++ b/libavfilter/vf_frei0r.c
@@ -353,6 +353,8 @@ static int config_input_props(AVFilterLink *inlink)
     AVFilterContext *ctx = inlink->dst;
     Frei0rContext *s = ctx->priv;
 
+    if (s->destruct && s->instance)
+        s->destruct(s->instance);
     if (!(s->instance = s->construct(inlink->w, inlink->h))) {
         av_log(ctx, AV_LOG_ERROR, "Impossible to load frei0r instance\n");
         return AVERROR(EINVAL);
@@ -487,6 +489,8 @@ static int source_config_props(AVFilterLink *outlink)
     outlink->time_base = s->time_base;
     outlink->sample_aspect_ratio = (AVRational){1,1};
 
+    if (s->destruct && s->instance)
+        s->destruct(s->instance);
     if (!(s->instance = s->construct(outlink->w, outlink->h))) {
         av_log(ctx, AV_LOG_ERROR, "Impossible to load frei0r instance\n");
         return AVERROR(EINVAL);
diff --git a/libavfilter/vf_gradfun.c b/libavfilter/vf_gradfun.c
index 6e92e3eed2..3abbd79e4f 100644
--- a/libavfilter/vf_gradfun.c
+++ b/libavfilter/vf_gradfun.c
@@ -168,6 +168,7 @@ static int config_input(AVFilterLink *inlink)
     int hsub = desc->log2_chroma_w;
     int vsub = desc->log2_chroma_h;
 
+    av_freep(&s->buf);
     s->buf = av_mallocz((FFALIGN(inlink->w, 16) * (s->radius + 1) / 2 + 32) * sizeof(uint16_t));
     if (!s->buf)
         return AVERROR(ENOMEM);
diff --git a/libavfilter/vf_lut.c b/libavfilter/vf_lut.c
index 7a6da5ec11..68320d0b41 100644
--- a/libavfilter/vf_lut.c
+++ b/libavfilter/vf_lut.c
@@ -221,6 +221,8 @@ static int config_props(AVFilterLink *inlink)
         int comp = s->is_rgb ? rgba_map[color] : color;
 
         /* create the parsed expression */
+        av_expr_free(s->comp_expr[color]);
+        s->comp_expr[color] = NULL;
         ret = av_expr_parse(&s->comp_expr[color], s->comp_expr_str[color],
                             var_names, funcs1_names, funcs1, NULL, NULL, 0, ctx);
         if (ret < 0) {