diff --git a/libavcodec/acelp_filters.c b/libavcodec/acelp_filters.c
index 9f720a5b96..0156d763fc 100644
--- a/libavcodec/acelp_filters.c
+++ b/libavcodec/acelp_filters.c
@@ -45,7 +45,7 @@ void ff_acelp_interpolate(int16_t* out, const int16_t* in,
 {
     int n, i;
 
-    assert(pitch_delay_frac >= 0 && pitch_delay_frac < precision);
+    assert(frac_pos >= 0 && frac_pos < precision);
 
     for (n = 0; n < length; n++) {
         int idx = 0;