diff --git a/src/com/google/javascript/jscomp/deps/ModuleLoader.java b/src/com/google/javascript/jscomp/deps/ModuleLoader.java
index 11d92f662af..7acdcb2f9bb 100644
--- a/src/com/google/javascript/jscomp/deps/ModuleLoader.java
+++ b/src/com/google/javascript/jscomp/deps/ModuleLoader.java
@@ -52,7 +52,7 @@ public final class ModuleLoader {
   public static final String DEFAULT_FILENAME_PREFIX = "." + MODULE_SLASH;
 
   public static final DiagnosticType LOAD_WARNING =
-      DiagnosticType.warning("JSC_JS_MODULE_LOAD_WARNING", "Failed to load module \"{0}\"");
+      DiagnosticType.error("JSC_JS_MODULE_LOAD_WARNING", "Failed to load module \"{0}\"");
 
   public static final DiagnosticType INVALID_MODULE_PATH =
       DiagnosticType.error(
diff --git a/test/com/google/javascript/jscomp/CompilerTest.java b/test/com/google/javascript/jscomp/CompilerTest.java
index da3a02708bc..793f56e4b0a 100644
--- a/test/com/google/javascript/jscomp/CompilerTest.java
+++ b/test/com/google/javascript/jscomp/CompilerTest.java
@@ -17,8 +17,8 @@
 package com.google.javascript.jscomp;
 
 import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
 
-import com.google.common.base.Charsets;
 import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -147,9 +147,9 @@ public void testCommonJSMissingRequire() throws Exception {
         inputs, ImmutableList.of(ModuleIdentifier.forFile("/gin")));
 
     ErrorManager manager = compiler.getErrorManager();
-    JSError[] warnings = manager.getWarnings();
-    assertThat(warnings).hasLength(1);
-    String error = warnings[0].toString();
+    JSError[] errors = manager.getErrors();
+    assertThat(errors).hasLength(1);
+    String error = errors[0].toString();
     assertThat(error).contains("Failed to load module \"missing\" at /gin.js");
   }
 
@@ -229,9 +229,9 @@ public void testResolveRelativeSourceMap() throws Exception {
     File tempDir = Files.createTempDir();
     String code = SOURCE_MAP_TEST_CODE + "\n//# sourceMappingURL=foo.js.map";
     File jsFile = new File(tempDir, "foo.js");
-    Files.asCharSink(jsFile, Charsets.UTF_8).write(code);
+    Files.asCharSink(jsFile, UTF_8).write(code);
     File sourceMapFile = new File(tempDir, "foo.js.map");
-    Files.asCharSink(sourceMapFile, Charsets.UTF_8).write(SOURCE_MAP);
+    Files.asCharSink(sourceMapFile, UTF_8).write(SOURCE_MAP);
 
     CompilerInput input = new CompilerInput(SourceFile.fromFile(jsFile.getAbsolutePath()));
     input.getAstRoot(compiler);
@@ -253,9 +253,9 @@ public void testResolveRelativeDirSourceMap() throws Exception {
     relativedir.mkdir();
     String code = SOURCE_MAP_TEST_CODE + "\n//# sourceMappingURL=relativedir/foo.js.map";
     File jsFile = new File(tempDir, "foo.js");
-    Files.asCharSink(jsFile, Charsets.UTF_8).write(code);
+    Files.asCharSink(jsFile, UTF_8).write(code);
     File sourceMapFile = new File(relativedir, "foo.js.map");
-    Files.asCharSink(sourceMapFile, Charsets.UTF_8).write(SOURCE_MAP);
+    Files.asCharSink(sourceMapFile, UTF_8).write(SOURCE_MAP);
 
     CompilerInput input = new CompilerInput(SourceFile.fromFile(jsFile.getAbsolutePath()));
     input.getAstRoot(compiler);
@@ -274,7 +274,7 @@ public void testMissingSourceMapFile() throws Exception {
     File tempDir = Files.createTempDir();
     String code = SOURCE_MAP_TEST_CODE + "\n//# sourceMappingURL=foo-does-not-exist.js.map";
     File jsFile = new File(tempDir, "foo2.js");
-    Files.asCharSink(jsFile, Charsets.UTF_8).write(code);
+    Files.asCharSink(jsFile, UTF_8).write(code);
 
     CompilerInput input = new CompilerInput(SourceFile.fromFile(jsFile.getAbsolutePath()));
     input.getAstRoot(compiler);
@@ -297,7 +297,7 @@ public void testNoWarningMissingAbsoluteSourceMap() throws Exception {
     File tempDir = Files.createTempDir();
     String code = SOURCE_MAP_TEST_CODE + "\n//# sourceMappingURL=/some/missing/path/foo.js.map";
     File jsFile = new File(tempDir, "foo.js");
-    Files.asCharSink(jsFile, Charsets.UTF_8).write(code);
+    Files.asCharSink(jsFile, UTF_8).write(code);
 
     CompilerInput input = new CompilerInput(SourceFile.fromFile(jsFile.getAbsolutePath()));
     input.getAstRoot(compiler);
diff --git a/test/com/google/javascript/jscomp/Es6RewriteModulesTest.java b/test/com/google/javascript/jscomp/Es6RewriteModulesTest.java
index 6be91572a29..423362793a8 100644
--- a/test/com/google/javascript/jscomp/Es6RewriteModulesTest.java
+++ b/test/com/google/javascript/jscomp/Es6RewriteModulesTest.java
@@ -95,7 +95,7 @@ public void testImport() {
   }
 
   public void testImport_missing() {
-    ModulesTestUtils.testModulesWarning(this, "import name from './does_not_exist';\n use(name);",
+    ModulesTestUtils.testModulesError(this, "import name from './does_not_exist';\n use(name);",
         ModuleLoader.LOAD_WARNING);
   }