Update c/enc/encode.c

Co-authored-by: Eugene Kliuchnikov <eustas@google.com>
diff --git a/c/enc/encode.c b/c/enc/encode.c
index a2cc7cb..a8fdcad 100644
--- a/c/enc/encode.c
+++ b/c/enc/encode.c
@@ -441,7 +441,7 @@
       static const double kMinEntropy = 7.92;
       const double bit_cost_threshold =
           (double)bytes * kMinEntropy * invKSampleRate;
-      size_t t = (bytes + kSampleRate - 1) * invKSampleRate;
+      size_t t = (double)(bytes + kSampleRate - 1) * invKSampleRate;
       uint32_t pos = (uint32_t)last_flush_pos;
       size_t i;
       for (i = 0; i < t; i++) {