diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 9353862c639..adbe8b56737 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -612,6 +612,9 @@ Release 2.8.0 - UNRELEASED
 
     HADOOP-11926. test-patch.sh mv does wrong math (aw)
 
+    HADOOP-11912. Extra configuration key used in TraceUtils should respect
+    prefix (Masatake Iwasaki via Colin P. McCabe)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/tracing/TraceUtils.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/tracing/TraceUtils.java
index fa52ac6762b..52b5d473161 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/tracing/TraceUtils.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/tracing/TraceUtils.java
@@ -47,18 +47,16 @@ public static HTraceConfiguration wrapHadoopConf(final String prefix,
     return new HTraceConfiguration() {
       @Override
       public String get(String key) {
-        if (extraMap.containsKey(key)) {
-          return extraMap.get(key);
-        }
-        return conf.get(prefix + key, "");
+        return get(key, "");
       }
 
       @Override
       public String get(String key, String defaultValue) {
-        if (extraMap.containsKey(key)) {
-          return extraMap.get(key);
+        String prefixedKey = prefix + key;
+        if (extraMap.containsKey(prefixedKey)) {
+          return extraMap.get(prefixedKey);
         }
-        return conf.get(prefix + key, defaultValue);
+        return conf.get(prefixedKey, defaultValue);
       }
     };
   }
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/tracing/TestTraceUtils.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/tracing/TestTraceUtils.java
index 80d64b16d32..400d003a2cb 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/tracing/TestTraceUtils.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/tracing/TestTraceUtils.java
@@ -46,7 +46,7 @@ public void testExtraConfig() {
     conf.set(TEST_PREFIX + key, oldValue);
     LinkedList<ConfigurationPair> extraConfig =
         new LinkedList<ConfigurationPair>();
-    extraConfig.add(new ConfigurationPair(key, newValue));
+    extraConfig.add(new ConfigurationPair(TEST_PREFIX + key, newValue));
     HTraceConfiguration wrapped = TraceUtils.wrapHadoopConf(TEST_PREFIX, conf, extraConfig);
     assertEquals(newValue, wrapped.get(key));
   }