diff --git a/check_api/src/main/java/com/google/errorprone/util/ASTHelpers.java b/check_api/src/main/java/com/google/errorprone/util/ASTHelpers.java
index 853a9f0bee2..cc44e4cbd47 100644
--- a/check_api/src/main/java/com/google/errorprone/util/ASTHelpers.java
+++ b/check_api/src/main/java/com/google/errorprone/util/ASTHelpers.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.errorprone.matchers.JUnitMatchers.JUNIT4_RUN_WITH_ANNOTATION;
 import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;
+import static java.util.Objects.requireNonNull;
 
 import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
@@ -144,6 +145,8 @@ public class ASTHelpers {
    * do any complex analysis here, just catch the obvious cases.
    */
   public static boolean sameVariable(ExpressionTree expr1, ExpressionTree expr2) {
+    requireNonNull(expr1);
+    requireNonNull(expr2);
     // Throw up our hands if we're not comparing identifiers and/or field accesses.
     if ((expr1.getKind() != Kind.IDENTIFIER && expr1.getKind() != Kind.MEMBER_SELECT)
         || (expr2.getKind() != Kind.IDENTIFIER && expr2.getKind() != Kind.MEMBER_SELECT)) {
diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/JdkObsolete.java b/core/src/main/java/com/google/errorprone/bugpatterns/JdkObsolete.java
index b49e0d8db45..1f078e5bf26 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/JdkObsolete.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/JdkObsolete.java
@@ -208,8 +208,11 @@ public Description matchClass(ClassTree tree, VisitorState state) {
 
   @Override
   public Description matchMemberReference(MemberReferenceTree tree, VisitorState state) {
-    Symbol sym = ASTHelpers.getSymbol(tree.getQualifierExpression());
-    return describeIfObsolete(tree.getQualifierExpression(), ImmutableList.of(sym.asType()), state);
+    Type type = ASTHelpers.getType(tree.getQualifierExpression());
+    if (type == null) {
+      return NO_MATCH;
+    }
+    return describeIfObsolete(tree.getQualifierExpression(), ImmutableList.of(type), state);
   }
 
   private Description describeIfObsolete(
diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/time/JavaDurationGetSecondsGetNano.java b/core/src/main/java/com/google/errorprone/bugpatterns/time/JavaDurationGetSecondsGetNano.java
index 7a33c9b7849..36f503b4f2b 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/time/JavaDurationGetSecondsGetNano.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/time/JavaDurationGetSecondsGetNano.java
@@ -124,7 +124,9 @@ public Boolean visitMethodInvocation(MethodInvocationTree tree, Void unused) {
               ExpressionTree getSecondsReceiver = ASTHelpers.getReceiver(tree);
               if (getSecondsReceiver != null) {
                 // if the methods are being invoked directly on the same variable...
-                if (ASTHelpers.sameVariable(getNanoReceiver, getSecondsReceiver)) {
+                if (getNanoReceiver != null
+                    && getSecondsReceiver != null
+                    && ASTHelpers.sameVariable(getNanoReceiver, getSecondsReceiver)) {
                   return true;
                 }
                 if (!checkProtoChains) {