diff --git a/libavfilter/boxblur.c b/libavfilter/boxblur.c
index 43c724daea..51029b93b4 100644
--- a/libavfilter/boxblur.c
+++ b/libavfilter/boxblur.c
@@ -114,9 +114,9 @@ int ff_boxblur_eval_filter_params(AVFilterLink *inlink,
 
 #define CHECK_RADIUS_VAL(w_, h_, comp)                                  \
     if (comp->radius < 0 ||                                   \
-        2*comp->radius > FFMIN(w_, h_)) {                     \
+        2*comp->radius >= FFMIN(w_, h_)) {                              \
         av_log(ctx, AV_LOG_ERROR,                                       \
-               "Invalid " #comp " radius value %d, must be >= 0 and <= %d\n", \
+               "Invalid " #comp " radius value %d, must be >= 0 and < %d\n", \
                comp->radius, FFMIN(w_, h_)/2);                \
         return AVERROR(EINVAL);                                         \
     }