diff --git a/src/core/meshcop/dataset.cpp b/src/core/meshcop/dataset.cpp
index 9140b74ea..4f19b6920 100644
--- a/src/core/meshcop/dataset.cpp
+++ b/src/core/meshcop/dataset.cpp
@@ -52,6 +52,7 @@ Dataset::Dataset(const Tlv::Type aType) :
     mLength(0),
     mType(aType)
 {
+    memset(mTlvs, 0, sizeof(mTlvs));
 }
 
 void Dataset::Clear(void)
diff --git a/tests/unit/test_platform.cpp b/tests/unit/test_platform.cpp
index 0fb701f65..dacafde17 100644
--- a/tests/unit/test_platform.cpp
+++ b/tests/unit/test_platform.cpp
@@ -495,7 +495,7 @@ exit:
         (void)aValue;
         (void)aValueLength;
 
-        return OT_ERROR_NONE;
+        return OT_ERROR_NOT_FOUND;
     }
 
     otError otPlatSettingsSet(otInstance *aInstance, uint16_t aKey, const uint8_t *aValue, uint16_t aValueLength)