diff --git a/libavcodec/g729dec.c b/libavcodec/g729dec.c
index 2e1bf18e4e..32218e5989 100644
--- a/libavcodec/g729dec.c
+++ b/libavcodec/g729dec.c
@@ -328,11 +328,14 @@ static int16_t g729d_voice_decision(int onset, int prev_voice_decision, const in
 
 static int32_t scalarproduct_int16_c(const int16_t * v1, const int16_t * v2, int order)
 {
-    int res = 0;
+    int64_t res = 0;
 
     while (order--)
         res += *v1++ * *v2++;
 
+    if      (res > INT32_MAX) return INT32_MAX;
+    else if (res < INT32_MIN) return INT32_MIN;
+
     return res;
 }