diff --git a/libavcodec/acelp_pitch_delay.c b/libavcodec/acelp_pitch_delay.c
index 3ecec01cbe..02a60e4ade 100644
--- a/libavcodec/acelp_pitch_delay.c
+++ b/libavcodec/acelp_pitch_delay.c
@@ -135,7 +135,7 @@ float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
         exp2f(M_LOG2_10 * 0.05 *
               (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) +
                energy_mean)) /
-        sqrtf(fixed_mean_energy);
+        sqrtf(fixed_mean_energy ? fixed_mean_energy : 1.0);
 
     // update quantified prediction error energy history
     memmove(&prediction_error[0], &prediction_error[1],