diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5e9b3b78..97cfebbc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+v5.1.19
+------
+* Explicitly set default value for TraceBuilder's ResultType to UNFINISHED to prevent null argument when building the trace in TraceBuilder.
+
 v5.1.18
 ------
 * Minor UI updates to trace visualizer to refresh JavaScript dependencies.
diff --git a/gradle.properties b/gradle.properties
index b4ebebe2..90bec905 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,3 +1,3 @@
-version=5.1.18
+version=5.1.19
 group=com.linkedin.parseq
 org.gradle.parallel=true
diff --git a/subprojects/parseq-lambda-names/src/main/java/com/linkedin/parseq/lambda/SourcePointer.java b/subprojects/parseq-lambda-names/src/main/java/com/linkedin/parseq/lambda/SourcePointer.java
index 0436564a..bfdc93fc 100644
--- a/subprojects/parseq-lambda-names/src/main/java/com/linkedin/parseq/lambda/SourcePointer.java
+++ b/subprojects/parseq-lambda-names/src/main/java/com/linkedin/parseq/lambda/SourcePointer.java
@@ -22,7 +22,7 @@ private SourcePointer(String className, String methodName, Integer lineNumber) {
         .findFirst()
         .map(SourcePointer::sourcePointer);
     if (!ret.isPresent()) {
-      System.out.println("WARNING： ParSeq cannot generate lambda function SourcePointer， "
+      System.out.println("WARNING: ParSeq cannot generate lambda function SourcePointer."
           + "source stacktrace will be printed:");
       exception.printStackTrace();
     }
diff --git a/subprojects/parseq/src/main/java/com/linkedin/parseq/trace/ShallowTraceBuilder.java b/subprojects/parseq/src/main/java/com/linkedin/parseq/trace/ShallowTraceBuilder.java
index a9b81e11..9785f87e 100644
--- a/subprojects/parseq/src/main/java/com/linkedin/parseq/trace/ShallowTraceBuilder.java
+++ b/subprojects/parseq/src/main/java/com/linkedin/parseq/trace/ShallowTraceBuilder.java
@@ -38,7 +38,7 @@ public class ShallowTraceBuilder {
   private volatile String _name;
   private volatile boolean _hidden;
   private volatile String _value;
-  private volatile ResultType _resultType;
+  private volatile ResultType _resultType = ResultType.UNFINISHED;
   private volatile long _startNanos = -1;
   private volatile long _pendingNanos = -1;
   private volatile long _endNanos = -1;