diff --git a/src/main/java/com/google/testing/compile/Compilation.java b/src/main/java/com/google/testing/compile/Compilation.java
index b00dc93d..57342b41 100644
--- a/src/main/java/com/google/testing/compile/Compilation.java
+++ b/src/main/java/com/google/testing/compile/Compilation.java
@@ -17,6 +17,7 @@
 
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.testing.compile.JavaFileObjects.asByteSource;
+import static java.util.Objects.requireNonNull;
 import static java.util.stream.Collectors.collectingAndThen;
 import static java.util.stream.Collectors.toList;
 import static javax.tools.Diagnostic.Kind.ERROR;
@@ -155,9 +156,8 @@ public Optional<JavaFileObject> generatedFile(Location location, String path) {
     // We're relying on the implementation of location.getName() to be equivalent to the first
     // part of the path.
     String expectedFilename = String.format("%s/%s", location.getName(), path);
-    return generatedFiles()
-        .stream()
-        .filter(generated -> generated.toUri().getPath().endsWith(expectedFilename))
+    return generatedFiles().stream()
+        .filter(generated -> requireNonNull(generated.toUri().getPath()).endsWith(expectedFilename))
         .findFirst();
   }
 
diff --git a/src/main/java/com/google/testing/compile/CompilationSubject.java b/src/main/java/com/google/testing/compile/CompilationSubject.java
index d8adad70..2fd3f393 100644
--- a/src/main/java/com/google/testing/compile/CompilationSubject.java
+++ b/src/main/java/com/google/testing/compile/CompilationSubject.java
@@ -26,6 +26,7 @@
 import static com.google.testing.compile.Compilation.Status.SUCCESS;
 import static com.google.testing.compile.JavaFileObjectSubject.javaFileObjects;
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Objects.requireNonNull;
 import static java.util.stream.Collectors.collectingAndThen;
 import static java.util.stream.Collectors.joining;
 import static java.util.stream.Collectors.toList;
@@ -338,7 +339,7 @@ private JavaFileObjectSubject checkGeneratedFile(
       facts.add(fact("in location", location.getName()));
       facts.add(simpleFact("it generated:"));
       for (JavaFileObject generated : actualNotNull().generatedFiles()) {
-        if (generated.toUri().getPath().contains(location.getName())) {
+        if (requireNonNull(generated.toUri().getPath()).contains(location.getName())) {
           facts.add(simpleFact("  " + generated.toUri().getPath()));
         }
       }
@@ -421,7 +422,8 @@ private ImmutableList<Diagnostic<? extends JavaFileObject>> findDiagnosticsInFil
           filterDiagnostics(
               diagnostic -> {
                 JavaFileObject source = diagnostic.getSource();
-                return source != null && source.toUri().getPath().equals(expectedFilePath);
+                return source != null
+                    && requireNonNull(source.toUri().getPath()).equals(expectedFilePath);
               });
       if (diagnosticsInFile.isEmpty()) {
         failExpectingMatchingDiagnostic(
diff --git a/src/main/java/com/google/testing/compile/InMemoryJavaFileManager.java b/src/main/java/com/google/testing/compile/InMemoryJavaFileManager.java
index c50e7817..d7f540a2 100644
--- a/src/main/java/com/google/testing/compile/InMemoryJavaFileManager.java
+++ b/src/main/java/com/google/testing/compile/InMemoryJavaFileManager.java
@@ -16,6 +16,7 @@
 package com.google.testing.compile;
 
 import static com.google.common.collect.MoreCollectors.toOptional;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.base.MoreObjects;
 import com.google.common.cache.CacheBuilder;
@@ -129,7 +130,7 @@ private Optional<JavaFileObject> findInMemoryInput(String packageName, String re
     String suffix =
         packageName.isEmpty() ? relativeName : packageName.replace('.', '/') + "/" + relativeName;
     return inMemoryInputs.entrySet().stream()
-        .filter(entry -> entry.getKey().getPath().endsWith(suffix))
+        .filter(entry -> requireNonNull(entry.getKey().getPath()).endsWith(suffix))
         .map(Map.Entry::getValue)
         .collect(toOptional()); // Might have problems if more than one input file matches.
   }
@@ -151,7 +152,8 @@ public JavaFileObject getJavaFileForOutput(Location location, String className,
   ImmutableList<JavaFileObject> getGeneratedSources() {
     ImmutableList.Builder<JavaFileObject> result = ImmutableList.builder();
     for (Map.Entry<URI, JavaFileObject> entry : inMemoryOutputs.asMap().entrySet()) {
-      if (entry.getKey().getPath().startsWith("/" + StandardLocation.SOURCE_OUTPUT.name())
+      if (requireNonNull(entry.getKey().getPath())
+              .startsWith("/" + StandardLocation.SOURCE_OUTPUT.name())
           && (entry.getValue().getKind() == Kind.SOURCE)) {
         result.add(entry.getValue());
       }
diff --git a/src/main/java/com/google/testing/compile/JavaFileObjectSubject.java b/src/main/java/com/google/testing/compile/JavaFileObjectSubject.java
index 7f8da2dd..29211b6f 100644
--- a/src/main/java/com/google/testing/compile/JavaFileObjectSubject.java
+++ b/src/main/java/com/google/testing/compile/JavaFileObjectSubject.java
@@ -23,6 +23,7 @@
 import static com.google.testing.compile.TreeDiffer.diffCompilationUnits;
 import static com.google.testing.compile.TreeDiffer.matchCompilationUnits;
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.io.ByteSource;
@@ -62,7 +63,7 @@ public static JavaFileObjectSubject assertThat(@Nullable JavaFileObject actual)
 
   @Override
   protected String actualCustomStringRepresentation() {
-    return actualNotNull().toUri().getPath();
+    return requireNonNull(actualNotNull().toUri().getPath());
   }
 
   /**
diff --git a/src/main/java/com/google/testing/compile/JavaFileObjects.java b/src/main/java/com/google/testing/compile/JavaFileObjects.java
index 81900c32..174bd1e5 100644
--- a/src/main/java/com/google/testing/compile/JavaFileObjects.java
+++ b/src/main/java/com/google/testing/compile/JavaFileObjects.java
@@ -17,6 +17,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 import static javax.tools.JavaFileObject.Kind.SOURCE;
 
 import com.google.common.base.CharMatcher;
@@ -162,7 +163,7 @@ public static JavaFileObject forResource(String resourceName) {
   }
 
   static Kind deduceKind(URI uri) {
-    String path = uri.getPath();
+    String path = requireNonNull(uri.getPath());
     for (Kind kind : Kind.values()) {
       if (path.endsWith(kind.extension)) {
         return kind;