diff --git a/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java b/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java
index 72b0b50..f3773a8 100644
--- a/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java
+++ b/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java
@@ -134,12 +134,7 @@
     var mdc = logRecord.getMdcCopy();
     var ndc = logRecord.getNdc();
 
-    var sourceLocation =
-        new LogEntry.SourceLocation(
-            logRecord.getSourceFileName(),
-            String.valueOf(logRecord.getSourceLineNumber()),
-            String.format(
-                "%s.%s", logRecord.getSourceClassName(), logRecord.getSourceMethodName()));
+    var sourceLocation = sourceLocationOf(logRecord);
 
     var entry =
         new LogEntry(
@@ -158,6 +153,22 @@
     return entry.json(json).build().toString() + "\n";
   }
 
+  private static LogEntry.SourceLocation sourceLocationOf(ExtLogRecord logRecord) {
+    var sourceFileName = logRecord.getSourceFileName();
+    var sourceLineNumber = logRecord.getSourceLineNumber();
+    var sourceClassName = logRecord.getSourceClassName();
+    var sourceMethodName = logRecord.getSourceMethodName();
+    return (sourceFileName == null
+            && sourceLineNumber <= 0
+            && sourceClassName == null
+            && sourceMethodName == null)
+        ? null
+        : new LogEntry.SourceLocation(
+            sourceFileName,
+            String.valueOf(sourceLineNumber),
+            String.format("%s.%s", sourceClassName, sourceMethodName));
+  }
+
   /**
    * Formats the log message corresponding to {@code logRecord} including a stack trace of the
    * {@link ExtLogRecord#getThrown()} exception if any.
diff --git a/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java b/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java
index 8517bde..8bcea2b 100644
--- a/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java
+++ b/core/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/LogEntry.java
@@ -30,7 +30,7 @@
   private final Timestamp timestamp;
   @Nullable private final String trace;
   @Nullable private final String spanId;
-  private final SourceLocation sourceLocation;
+  @Nullable private final SourceLocation sourceLocation;
   private final Map<String, String> labels;
   private final List<StructuredParameter> parameters;
   private final Map<String, String> mappedDiagnosticContext;
@@ -43,7 +43,7 @@
       Timestamp timestamp,
       @Nullable String trace,
       @Nullable String spanId,
-      SourceLocation sourceLocation,
+      @Nullable SourceLocation sourceLocation,
       Map<String, String> labels,
       List<StructuredParameter> parameters,
       Map<String, String> mappedDiagnosticContext,
@@ -135,11 +135,13 @@
       b.add("@type", type);
     }
 
-    return b.add("message", message)
-        .add("severity", severity)
-        .add("timestamp", timestamp.json(json))
-        .add("logging.googleapis.com/sourceLocation", sourceLocation.json(json))
-        .addAll(jsonOfStringMap(json, mappedDiagnosticContext))
+    b.add("message", message).add("severity", severity).add("timestamp", timestamp.json(json));
+
+    if (sourceLocation != null) {
+      b.add("logging.googleapis.com/sourceLocation", sourceLocation.json(json));
+    }
+
+    return b.addAll(jsonOfStringMap(json, mappedDiagnosticContext))
         .addAll(jsonOfParameterMap(json, parameters));
   }