diff --git a/concurrency-limits-core/build.gradle b/concurrency-limits-core/build.gradle
index c3863819..11bf0bbf 100644
--- a/concurrency-limits-core/build.gradle
+++ b/concurrency-limits-core/build.gradle
@@ -5,5 +5,7 @@ plugins {
 sourceCompatibility = JavaVersion.VERSION_1_8
 
 dependencies {
+    compile "org.slf4j:slf4j-api:1.7.+"
+    
     testCompile 'junit:junit-dep:4.10'
 }
diff --git a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/MetricRegistry.java b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/MetricRegistry.java
index 35b82259..e6b232e1 100644
--- a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/MetricRegistry.java
+++ b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/MetricRegistry.java
@@ -26,12 +26,20 @@ interface SampleListener {
     SampleListener registerDistribution(String id, String... tagNameValuePairs);
     
     /**
-     * Register a guage using the provided supplier.  The supplier will be polled whenever the guage
+     * Register a gauge using the provided supplier.  The supplier will be polled whenever the guage
      * value is flushed by the registry.
      * 
      * @param id
      * @param tagNameValuePairs Pairs of tag name and tag value.  Number of parameters must be a multiple of 2.
      * @param supplier
      */
-    void registerGuage(String id, Supplier<Number> supplier, String... tagNameValuePairs);
+    void registerGauge(String id, Supplier<Number> supplier, String... tagNameValuePairs);
+    
+    /**
+     * @deprecated Call MetricRegistry#registerGauge
+     */
+    @Deprecated
+    default void registerGuage(String id, Supplier<Number> supplier, String... tagNameValuePairs) {
+        registerGauge(id, supplier, tagNameValuePairs);
+    }
 }
diff --git a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/internal/EmptyMetricRegistry.java b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/internal/EmptyMetricRegistry.java
index a2821bbf..84be8d59 100644
--- a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/internal/EmptyMetricRegistry.java
+++ b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/internal/EmptyMetricRegistry.java
@@ -15,6 +15,6 @@ public SampleListener registerDistribution(String id, String... tagNameValuePair
     }
 
     @Override
-    public void registerGuage(String id, Supplier<Number> supplier, String... tagNameValuePairs) {
+    public void registerGauge(String id, Supplier<Number> supplier, String... tagNameValuePairs) {
     }
 }
diff --git a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/limit/VegasLimit.java b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/limit/VegasLimit.java
index 2a7fd9d6..39e21dba 100644
--- a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/limit/VegasLimit.java
+++ b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/limit/VegasLimit.java
@@ -74,7 +74,7 @@ public static VegasLimit newDefault() {
      */
     private volatile int estimatedLimit;
     
-    private long rtt_noload;
+    private volatile long rtt_noload;
     
     private boolean didDrop = false;
     
diff --git a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/LookupPartitionStrategy.java b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/LookupPartitionStrategy.java
index a85a7033..880e88b7 100644
--- a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/LookupPartitionStrategy.java
+++ b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/LookupPartitionStrategy.java
@@ -72,7 +72,7 @@ private LookupPartitionStrategy(Builder<T> builder) {
         
         this.lookup = builder.lookup;
         
-        builder.registry.registerGuage(MetricIds.LIMIT_GUAGE_NAME, this::getLimit);
+        builder.registry.registerGauge(MetricIds.LIMIT_GUAGE_NAME, this::getLimit);
     }
     
     @Override
@@ -118,7 +118,7 @@ public Partition(String name, double pct) {
         
         public void createMetrics(MetricRegistry registry) {
             this.busyDistribution = registry.registerDistribution(MetricIds.INFLIGHT_GUAGE_NAME, PARTITION_TAG_NAME, name);
-            registry.registerGuage(MetricIds.PARTITION_LIMIT_GUAGE_NAME, this::getLimit, PARTITION_TAG_NAME, name);
+            registry.registerGauge(MetricIds.PARTITION_LIMIT_GUAGE_NAME, this::getLimit, PARTITION_TAG_NAME, name);
         }
         
         public void updateLimit(int totalLimit) {
diff --git a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/PredicatePartitionStrategy.java b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/PredicatePartitionStrategy.java
index 82fb2128..19641b1c 100644
--- a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/PredicatePartitionStrategy.java
+++ b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/PredicatePartitionStrategy.java
@@ -65,7 +65,7 @@ private PredicatePartitionStrategy(Builder<T> builder) {
         this.partitions = new ArrayList<>(builder.partitions);
         this.partitions.forEach(partition -> partition.createMetrics(builder.registry));
         
-        builder.registry.registerGuage(MetricIds.LIMIT_GUAGE_NAME, this::getLimit);
+        builder.registry.registerGauge(MetricIds.LIMIT_GUAGE_NAME, this::getLimit);
     }
     
     @Override
@@ -116,7 +116,7 @@ public Partition(String name, double pct, Predicate<T> predicate) {
         
         public void createMetrics(MetricRegistry registry) {
             this.inflightDistribution = registry.registerDistribution(MetricIds.INFLIGHT_GUAGE_NAME, PARTITION_TAG_NAME, name);
-            registry.registerGuage(MetricIds.PARTITION_LIMIT_GUAGE_NAME, this::getLimit, PARTITION_TAG_NAME, name);
+            registry.registerGauge(MetricIds.PARTITION_LIMIT_GUAGE_NAME, this::getLimit, PARTITION_TAG_NAME, name);
         }
         
         public void updateLimit(int totalLimit) {
diff --git a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/SimpleStrategy.java b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/SimpleStrategy.java
index 90972ff7..3096ac52 100644
--- a/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/SimpleStrategy.java
+++ b/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/strategy/SimpleStrategy.java
@@ -25,7 +25,7 @@ public SimpleStrategy() {
     
     public SimpleStrategy(MetricRegistry registry) {
         this.inflightMetric = registry.registerDistribution(MetricIds.INFLIGHT_GUAGE_NAME);
-        registry.registerGuage(MetricIds.LIMIT_GUAGE_NAME, this::getLimit);
+        registry.registerGauge(MetricIds.LIMIT_GUAGE_NAME, this::getLimit);
     }
     
     @Override
diff --git a/concurrency-limits-grpc/build.gradle b/concurrency-limits-grpc/build.gradle
index d9913309..89152bb6 100644
--- a/concurrency-limits-grpc/build.gradle
+++ b/concurrency-limits-grpc/build.gradle
@@ -7,11 +7,11 @@ sourceCompatibility = JavaVersion.VERSION_1_8
 dependencies {
     compile project(":concurrency-limits-core")
 
-    compile "io.grpc:grpc-core:1.3.1"
+    compile "io.grpc:grpc-core:1.9.0"
     
     testCompile project(":concurrency-limits-spectator")
     
-    testCompile "io.grpc:grpc-netty:1.3.1"
-    testCompile "io.grpc:grpc-stub:1.3.1"
+    testCompile "io.grpc:grpc-netty:1.9.0"
+    testCompile "io.grpc:grpc-stub:1.9.0"
     testCompile "junit:junit-dep:4.10"
 }
diff --git a/concurrency-limits-spectator/src/main/java/com/netflix/concurrency/limits/spectator/SpectatorMetricRegistry.java b/concurrency-limits-spectator/src/main/java/com/netflix/concurrency/limits/spectator/SpectatorMetricRegistry.java
index cc0516dc..56ad4b25 100644
--- a/concurrency-limits-spectator/src/main/java/com/netflix/concurrency/limits/spectator/SpectatorMetricRegistry.java
+++ b/concurrency-limits-spectator/src/main/java/com/netflix/concurrency/limits/spectator/SpectatorMetricRegistry.java
@@ -8,6 +8,9 @@
 
 import java.util.function.Supplier;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 public final class SpectatorMetricRegistry implements MetricRegistry {
     private final Registry registry;
     private final Id baseId;
@@ -24,10 +27,10 @@ public SampleListener registerDistribution(String id, String... tagNameValuePair
     }
 
     @Override
-    public void registerGuage(String id, Supplier<Number> supplier, String... tagNameValuePairs) {
+    public void registerGauge(String id, Supplier<Number> supplier, String... tagNameValuePairs) {
         PolledMeter.using(registry)
             .withId(suffixBaseId(id).withTags(tagNameValuePairs))
-            .monitorValue(this, o -> supplier.get().doubleValue());
+            .monitorValue(supplier, ignore -> supplier.get().doubleValue());
     }
     
     private Id suffixBaseId(String suffix) {
diff --git a/concurrency-limits-spectator/src/test/java/com/netflix/concurrency/limits/spectator/SpectatorMetricRegistryTest.java b/concurrency-limits-spectator/src/test/java/com/netflix/concurrency/limits/spectator/SpectatorMetricRegistryTest.java
index 343c9260..3495c5fc 100644
--- a/concurrency-limits-spectator/src/test/java/com/netflix/concurrency/limits/spectator/SpectatorMetricRegistryTest.java
+++ b/concurrency-limits-spectator/src/test/java/com/netflix/concurrency/limits/spectator/SpectatorMetricRegistryTest.java
@@ -12,7 +12,7 @@ public void testGuage() {
         DefaultRegistry registry = new DefaultRegistry();
         SpectatorMetricRegistry metricRegistry = new SpectatorMetricRegistry(registry, registry.createId("foo"));
         
-        metricRegistry.registerGuage("bar", () -> 10);
+        metricRegistry.registerGauge("bar", () -> 10);
         
         PolledMeter.update(registry);