Explicit conversion

Test: m tests
Change-Id: Ie0c00a51dee1d97239b0ef6f29334d176ddec32a
diff --git a/vibrator/aidl/vts/VtsHalVibratorTargetTest.cpp b/vibrator/aidl/vts/VtsHalVibratorTargetTest.cpp
index 791d7e8..f50a5e7 100644
--- a/vibrator/aidl/vts/VtsHalVibratorTargetTest.cpp
+++ b/vibrator/aidl/vts/VtsHalVibratorTargetTest.cpp
@@ -444,7 +444,7 @@
 
             effect.delayMs = std::rand() % (maxDelay + 1);
             effect.primitive = primitive;
-            effect.scale = static_cast<float>(std::rand()) / RAND_MAX;
+            effect.scale = static_cast<float>(std::rand()) / static_cast<float>(RAND_MAX);
             composite.emplace_back(effect);
 
             if (composite.size() == maxSize) {