diff --git a/thermal/1.0/default/Thermal.cpp b/thermal/1.0/default/Thermal.cpp
index 8a8ad0a..2dd0090 100644
--- a/thermal/1.0/default/Thermal.cpp
+++ b/thermal/1.0/default/Thermal.cpp
@@ -17,6 +17,7 @@
 #define LOG_TAG "android.hardware.thermal@1.0-impl"
 
 #include <errno.h>
+#include <math.h>
 
 #include <vector>
 
@@ -33,6 +34,14 @@
 namespace V1_0 {
 namespace implementation {
 
+namespace {
+
+float finalizeTemperature(float temperature) {
+    return temperature == UNKNOWN_TEMPERATURE ? NAN : temperature;
+}
+
+}
+
 Thermal::Thermal(thermal_module_t* module) : mModule(module) {}
 
 // Methods from ::android::hardware::thermal::V1_0::IThermal follow.
@@ -76,10 +85,11 @@
             ;
         }
         temperatures[i].name = list[i].name;
-        temperatures[i].currentValue = list[i].current_value;
-        temperatures[i].throttlingThreshold = list[i].throttling_threshold;
-        temperatures[i].shutdownThreshold = list[i].shutdown_threshold;
-        temperatures[i].vrThrottlingThreshold = list[i].vr_throttling_threshold;
+        temperatures[i].currentValue = finalizeTemperature(list[i].current_value);
+        temperatures[i].throttlingThreshold = finalizeTemperature(list[i].throttling_threshold);
+        temperatures[i].shutdownThreshold = finalizeTemperature(list[i].shutdown_threshold);
+        temperatures[i].vrThrottlingThreshold =
+                finalizeTemperature(list[i].vr_throttling_threshold);
       }
     }
   }
diff --git a/thermal/1.0/types.hal b/thermal/1.0/types.hal
index 8864f43..eb5d7c7 100644
--- a/thermal/1.0/types.hal
+++ b/thermal/1.0/types.hal
@@ -45,28 +45,27 @@
     string name;
 
     /**
-     * Current temperature in Celsius. If not available set by HAL to
-     * UNKNOWN_TEMPERATURE.
+     * Current temperature in Celsius. If not available set by HAL to NAN.
      * Current temperature can be in any units if type=UNKNOWN.
      */
     float currentValue;
 
     /**
      * Throttling temperature constant for this temperature.
-     * If not available, set by HAL to UNKNOWN_TEMPERATURE.
+     * If not available, set by HAL to NAN.
      */
     float throttlingThreshold;
 
     /**
      * Shutdown temperature constant for this temperature.
-     * If not available, set by HAL to UNKNOWN_TEMPERATURE.
+     * If not available, set by HAL to NAN.
      */
     float shutdownThreshold;
 
     /**
      * Threshold temperature above which the VR mode clockrate minimums cannot
      * be maintained for this device.
-     * If not available, set by HAL to UNKNOWN_TEMPERATURE.
+     * If not available, set by HAL to NAN.
      */
     float vrThrottlingThreshold;
 
@@ -135,7 +134,3 @@
      */
     string debugMessage;
 };
-
-/**
- * TODO(pbond): add float constant UNDEFINED_TEMPERATURE.
- */
diff --git a/thermal/1.0/vts/functional/thermal_hidl_hal_test.cpp b/thermal/1.0/vts/functional/thermal_hidl_hal_test.cpp
index 8a5ea2c..d922169 100644
--- a/thermal/1.0/vts/functional/thermal_hidl_hal_test.cpp
+++ b/thermal/1.0/vts/functional/thermal_hidl_hal_test.cpp
@@ -43,8 +43,6 @@
 #define THERMAL_SERVICE_NAME "thermal"
 #define MONITORING_OPERATION_NUMBER 10
 
-#define UNDEFINED_TEMPERATURE (-FLT_MAX)
-
 #define MAX_DEVICE_TEMPERATURE 200
 #define MAX_FAN_SPEED 20000
 
@@ -127,21 +125,18 @@
     // .currentValue of known type is in Celsius and must be reasonable.
     EXPECT_TRUE(temperature.type == TemperatureType::UNKNOWN ||
                 std::abs(temperature.currentValue) < MAX_DEVICE_TEMPERATURE ||
-                temperature.currentValue == UNDEFINED_TEMPERATURE);
+                isnan(temperature.currentValue));
 
     // .name must not be empty.
     EXPECT_LT(0u, temperature.name.size());
 
     // .currentValue must not exceed .shutdwonThreshold if defined.
     EXPECT_TRUE(temperature.currentValue < temperature.shutdownThreshold ||
-                temperature.currentValue == UNDEFINED_TEMPERATURE ||
-                temperature.shutdownThreshold == UNDEFINED_TEMPERATURE);
+                isnan(temperature.currentValue) || isnan(temperature.shutdownThreshold));
 
     // .throttlingThreshold must not exceed .shutdownThreshold if defined.
-    EXPECT_TRUE(temperature.throttlingThreshold <
-                    temperature.shutdownThreshold ||
-                temperature.throttlingThreshold == UNDEFINED_TEMPERATURE ||
-                temperature.shutdownThreshold == UNDEFINED_TEMPERATURE);
+    EXPECT_TRUE(temperature.throttlingThreshold < temperature.shutdownThreshold ||
+                isnan(temperature.throttlingThreshold) || isnan(temperature.shutdownThreshold));
   }
 
   // Check validity of CPU usage returned by Thermal HAL.