diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/metrics/api/JavaClassMetricKey.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/metrics/api/JavaClassMetricKey.java
index 501c1a05a3..38e2c9ef8f 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/metrics/api/JavaClassMetricKey.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/metrics/api/JavaClassMetricKey.java
@@ -111,7 +111,7 @@ public enum JavaClassMetricKey implements MetricKey<ASTAnyTypeDeclaration> {
 
             @Override
             public int hashCode() {
-                return metric.hashCode() * 31 + name.hashCode();
+                return (metric != null ? metric.hashCode() * 31 : 0) + (name != null ? name.hashCode() : 0);
             }
         };
     }
diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/metrics/api/JavaOperationMetricKey.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/metrics/api/JavaOperationMetricKey.java
index f4c1680696..3ab49b3c3f 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/metrics/api/JavaOperationMetricKey.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/metrics/api/JavaOperationMetricKey.java
@@ -115,7 +115,7 @@ public enum JavaOperationMetricKey implements MetricKey<ASTMethodOrConstructorDe
 
             @Override
             public int hashCode() {
-                return metric.hashCode() * 31 + name.hashCode();
+                return (metric != null ? metric.hashCode() * 31 : 0) + (name != null ? name.hashCode() : 0);
             }
 
         };