diff --git a/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderTest.java b/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderTest.java
index 2e92de0..fdf64e6 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/LocationExpanderTest.java
@@ -18,6 +18,7 @@
 
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.LocationExpander.LocationFunction;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import java.util.ArrayList;
 import java.util.List;
@@ -73,7 +74,7 @@
         ImmutableMap.<String, LocationFunction>of(
             "location", f1,
             "locations", f2),
-        ImmutableMap.of());
+        RepositoryMapping.ALWAYS_FALLBACK);
   }
 
   private String expand(String input) throws Exception {
@@ -133,10 +134,11 @@
         RepositoryName.create("@foo"),
         RepositoryName.create("@bar"));
 
-    LocationExpander locationExpander = new LocationExpander(
-        new Capture(),
-        ImmutableMap.<String, LocationFunction>of("location", f1),
-        repositoryMapping);
+    LocationExpander locationExpander =
+        new LocationExpander(
+            new Capture(),
+            ImmutableMap.<String, LocationFunction>of("location", f1),
+            RepositoryMapping.createAllowingFallback(repositoryMapping));
 
     String value = locationExpander.expand("$(location @foo//a)");
     assertThat(value).isEqualTo("src/a");
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/LocationFunctionTest.java b/src/test/java/com/google/devtools/build/lib/analysis/LocationFunctionTest.java
index 311ae2e..c333ad7 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/LocationFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/LocationFunctionTest.java
@@ -25,6 +25,7 @@
 import com.google.devtools.build.lib.actions.util.ActionsTestUtil;
 import com.google.devtools.build.lib.analysis.LocationExpander.LocationFunction;
 import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.vfs.DigestHashFunction;
 import com.google.devtools.build.lib.vfs.FileSystem;
@@ -47,23 +48,25 @@
   public void absoluteAndRelativeLabels() throws Exception {
     LocationFunction func =
         new LocationFunctionBuilder("//foo", false).add("//foo", "/exec/src/bar").build();
-    assertThat(func.apply("//foo", ImmutableMap.of())).isEqualTo("src/bar");
-    assertThat(func.apply(":foo", ImmutableMap.of())).isEqualTo("src/bar");
-    assertThat(func.apply("foo", ImmutableMap.of())).isEqualTo("src/bar");
+    assertThat(func.apply("//foo", RepositoryMapping.ALWAYS_FALLBACK)).isEqualTo("src/bar");
+    assertThat(func.apply(":foo", RepositoryMapping.ALWAYS_FALLBACK)).isEqualTo("src/bar");
+    assertThat(func.apply("foo", RepositoryMapping.ALWAYS_FALLBACK)).isEqualTo("src/bar");
   }
 
   @Test
   public void pathUnderExecRootUsesDotSlash() throws Exception {
     LocationFunction func =
         new LocationFunctionBuilder("//foo", false).add("//foo", "/exec/bar").build();
-    assertThat(func.apply("//foo", ImmutableMap.of())).isEqualTo("./bar");
+    assertThat(func.apply("//foo", RepositoryMapping.ALWAYS_FALLBACK)).isEqualTo("./bar");
   }
 
   @Test
   public void noSuchLabel() throws Exception {
     LocationFunction func = new LocationFunctionBuilder("//foo", false).build();
     IllegalStateException expected =
-        assertThrows(IllegalStateException.class, () -> func.apply("//bar", ImmutableMap.of()));
+        assertThrows(
+            IllegalStateException.class,
+            () -> func.apply("//bar", RepositoryMapping.ALWAYS_FALLBACK));
     assertThat(expected)
         .hasMessageThat()
         .isEqualTo(
@@ -75,7 +78,9 @@
   public void emptyList() throws Exception {
     LocationFunction func = new LocationFunctionBuilder("//foo", false).add("//foo").build();
     IllegalStateException expected =
-        assertThrows(IllegalStateException.class, () -> func.apply("//foo", ImmutableMap.of()));
+        assertThrows(
+            IllegalStateException.class,
+            () -> func.apply("//foo", RepositoryMapping.ALWAYS_FALLBACK));
     assertThat(expected)
         .hasMessageThat()
         .isEqualTo("label '//foo:foo' in $(location) expression expands to no files");
@@ -86,7 +91,9 @@
     LocationFunction func =
         new LocationFunctionBuilder("//foo", false).add("//foo", "/exec/1", "/exec/2").build();
     IllegalStateException expected =
-        assertThrows(IllegalStateException.class, () -> func.apply("//foo", ImmutableMap.of()));
+        assertThrows(
+            IllegalStateException.class,
+            () -> func.apply("//foo", RepositoryMapping.ALWAYS_FALLBACK));
     assertThat(expected)
         .hasMessageThat()
         .isEqualTo(
@@ -99,7 +106,9 @@
   public void noSuchLabelMultiple() throws Exception {
     LocationFunction func = new LocationFunctionBuilder("//foo", true).build();
     IllegalStateException expected =
-        assertThrows(IllegalStateException.class, () -> func.apply("//bar", ImmutableMap.of()));
+        assertThrows(
+            IllegalStateException.class,
+            () -> func.apply("//bar", RepositoryMapping.ALWAYS_FALLBACK));
     assertThat(expected)
         .hasMessageThat()
         .isEqualTo(
@@ -111,7 +120,8 @@
   public void fileWithSpace() throws Exception {
     LocationFunction func =
         new LocationFunctionBuilder("//foo", false).add("//foo", "/exec/file/with space").build();
-    assertThat(func.apply("//foo", ImmutableMap.of())).isEqualTo("'file/with space'");
+    assertThat(func.apply("//foo", RepositoryMapping.ALWAYS_FALLBACK))
+        .isEqualTo("'file/with space'");
   }
 
   @Test
@@ -119,7 +129,8 @@
     LocationFunction func = new LocationFunctionBuilder("//foo", true)
         .add("//foo", "/exec/foo/bar", "/exec/out/foo/foobar")
         .build();
-    assertThat(func.apply("//foo", ImmutableMap.of())).isEqualTo("foo/bar foo/foobar");
+    assertThat(func.apply("//foo", RepositoryMapping.ALWAYS_FALLBACK))
+        .isEqualTo("foo/bar foo/foobar");
   }
 
   @Test
@@ -127,7 +138,7 @@
     LocationFunction func = new LocationFunctionBuilder("//foo", true)
         .add("//foo", "/exec/file/with space", "/exec/file/with spaces ")
         .build();
-    assertThat(func.apply("//foo", ImmutableMap.of()))
+    assertThat(func.apply("//foo", RepositoryMapping.ALWAYS_FALLBACK))
         .isEqualTo("'file/with space' 'file/with spaces '");
   }
 
@@ -137,7 +148,8 @@
         .setExecPaths(true)
         .add("//foo", "/exec/bar", "/exec/out/foobar")
         .build();
-    assertThat(func.apply("//foo", ImmutableMap.of())).isEqualTo("./bar out/foobar");
+    assertThat(func.apply("//foo", RepositoryMapping.ALWAYS_FALLBACK))
+        .isEqualTo("./bar out/foobar");
   }
 
   @Test
@@ -147,7 +159,8 @@
     ImmutableMap<RepositoryName, RepositoryName> repositoryMapping = ImmutableMap.of(a, b);
     LocationFunction func =
         new LocationFunctionBuilder("//foo", false).add("@b//foo", "/exec/src/bar").build();
-    assertThat(func.apply("@a//foo", repositoryMapping)).isEqualTo("src/bar");
+    assertThat(func.apply("@a//foo", RepositoryMapping.createAllowingFallback(repositoryMapping)))
+        .isEqualTo("src/bar");
   }
 
   @Test
@@ -157,7 +170,9 @@
     ImmutableMap<RepositoryName, RepositoryName> repositoryMapping = ImmutableMap.of(a, b);
     LocationFunction func =
         new LocationFunctionBuilder("//foo", false).add("@potato//foo", "/exec/src/bar").build();
-    assertThat(func.apply("@potato//foo", repositoryMapping)).isEqualTo("src/bar");
+    assertThat(
+            func.apply("@potato//foo", RepositoryMapping.createAllowingFallback(repositoryMapping)))
+        .isEqualTo("src/bar");
   }
 }
 
diff --git a/src/test/java/com/google/devtools/build/lib/cmdline/RepositoryMappingTest.java b/src/test/java/com/google/devtools/build/lib/cmdline/RepositoryMappingTest.java
new file mode 100644
index 0000000..c7cb715
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/cmdline/RepositoryMappingTest.java
@@ -0,0 +1,47 @@
+// Copyright 2021 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.cmdline;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.ImmutableMap;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests for @{link RepositoryMapping}. */
+@RunWith(JUnit4.class)
+public final class RepositoryMappingTest {
+
+  @Test
+  public void maybeFallback() throws Exception {
+    RepositoryMapping mapping =
+        RepositoryMapping.createAllowingFallback(
+            ImmutableMap.of(RepositoryName.create("@A"), RepositoryName.create("@com_foo_bar_a")));
+    assertThat(mapping.get(RepositoryName.create("@A")))
+        .isEqualTo(RepositoryName.create("@com_foo_bar_a"));
+    assertThat(mapping.get(RepositoryName.create("@B"))).isEqualTo(RepositoryName.create("@B"));
+  }
+
+  @Test
+  public void neverFallback() throws Exception {
+    RepositoryMapping mapping =
+        RepositoryMapping.create(
+            ImmutableMap.of(RepositoryName.create("@A"), RepositoryName.create("@com_foo_bar_a")));
+    assertThat(mapping.get(RepositoryName.create("@A")))
+        .isEqualTo(RepositoryName.create("@com_foo_bar_a"));
+    assertThat(mapping.get(RepositoryName.create("@B"))).isNull();
+  }
+}
diff --git a/src/test/java/com/google/devtools/build/lib/cmdline/TargetPatternTest.java b/src/test/java/com/google/devtools/build/lib/cmdline/TargetPatternTest.java
index 4b07663..b7654fa 100644
--- a/src/test/java/com/google/devtools/build/lib/cmdline/TargetPatternTest.java
+++ b/src/test/java/com/google/devtools/build/lib/cmdline/TargetPatternTest.java
@@ -20,7 +20,6 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.cmdline.TargetPattern.TargetsBelowDirectory;
 import com.google.devtools.build.lib.cmdline.TargetPattern.TargetsBelowDirectory.ContainsResult;
-import java.util.Map;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -167,10 +166,11 @@
 
   @Test
   public void testRenameRepository() throws Exception {
-    Map<RepositoryName, RepositoryName> renaming =
-        ImmutableMap.of(
-            RepositoryName.create("@foo"), RepositoryName.create("@bar"),
-            RepositoryName.create("@myworkspace"), RepositoryName.create("@"));
+    RepositoryMapping renaming =
+        RepositoryMapping.createAllowingFallback(
+            ImmutableMap.of(
+                RepositoryName.create("@foo"), RepositoryName.create("@bar"),
+                RepositoryName.create("@myworkspace"), RepositoryName.create("@")));
 
     // Expecting renaming
     assertThat(TargetPattern.renameRepository("@foo//package:target", renaming))
diff --git a/src/test/java/com/google/devtools/build/lib/packages/BuildTypeTest.java b/src/test/java/com/google/devtools/build/lib/packages/BuildTypeTest.java
index 8b54a24..316936d 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/BuildTypeTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/BuildTypeTest.java
@@ -22,6 +22,7 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.packages.BuildType.LabelConversionContext;
 import com.google.devtools.build.lib.packages.BuildType.Selector;
@@ -46,7 +47,7 @@
   private final LabelConversionContext labelConversionContext =
       new LabelConversionContext(
           currentRule,
-          /*repositoryMapping=*/ ImmutableMap.of(),
+          RepositoryMapping.ALWAYS_FALLBACK,
           /*convertedLabelsInPackage=*/ new HashMap<>());
 
   @Test
@@ -273,8 +274,9 @@
     LabelConversionContext context =
         new LabelConversionContext(
             currentRule,
-            ImmutableMap.of(
-                RepositoryName.create("@orig_repo"), RepositoryName.create("@new_repo")),
+            RepositoryMapping.createAllowingFallback(
+                ImmutableMap.of(
+                    RepositoryName.create("@orig_repo"), RepositoryName.create("@new_repo"))),
             /* convertedLabelsInPackage= */ new HashMap<>());
     Label label = BuildType.LABEL.convert("@orig_repo//foo:bar", null, context);
     assertThat(label)
diff --git a/src/test/java/com/google/devtools/build/lib/packages/PackageTest.java b/src/test/java/com/google/devtools/build/lib/packages/PackageTest.java
index 8b8f190..3d33e49 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/PackageTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/PackageTest.java
@@ -18,9 +18,9 @@
 import static org.mockito.Mockito.mock;
 
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.events.StoredEventHandler;
 import com.google.devtools.build.lib.packages.Package.Builder.DefaultPackageSettings;
 import com.google.devtools.build.lib.packages.RuleClass.Builder.RuleClassType;
@@ -164,7 +164,7 @@
             PackageIdentifier.createInMainRepo(name),
             "workspace",
             /*noImplicitFileExport=*/ true,
-            ImmutableMap.of());
+            RepositoryMapping.ALWAYS_FALLBACK);
     result.setFilename(
         RootedPath.toRootedPath(
             Root.fromPath(fileSystem.getPath("/irrelevantRoot")), PathFragment.create(name)));
diff --git a/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java b/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
index eddb34c..23a8192 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
@@ -45,6 +45,7 @@
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventCollector;
 import com.google.devtools.build.lib.events.EventKind;
@@ -264,7 +265,7 @@
             PackageIdentifier.createInMainRepo(TEST_PACKAGE_NAME),
             "TESTING",
             StarlarkSemantics.DEFAULT,
-            /*repositoryMapping=*/ ImmutableMap.of())
+            RepositoryMapping.ALWAYS_FALLBACK)
         .setFilename(RootedPath.toRootedPath(root, testBuildfilePath));
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java b/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java
index 52c9666..df85e78 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java
@@ -26,6 +26,7 @@
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelConstants;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.events.Reporter;
 import com.google.devtools.build.lib.packages.RuleFactory.BuildLangTypedAttributeValuesMap;
 import com.google.devtools.build.lib.packages.util.PackageLoadingTestCase;
@@ -58,7 +59,7 @@
   private Package.Builder newBuilder(PackageIdentifier id, Path filename) {
     return packageFactory
         .newPackageBuilder(
-            id, "TESTING", StarlarkSemantics.DEFAULT, /* repositoryMapping= */ ImmutableMap.of())
+            id, "TESTING", StarlarkSemantics.DEFAULT, RepositoryMapping.ALWAYS_FALLBACK)
         .setFilename(RootedPath.toRootedPath(root, filename));
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/RepositoryMappingFunctionTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/RepositoryMappingFunctionTest.java
index 1f65555..45ddd97 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/RepositoryMappingFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/RepositoryMappingFunctionTest.java
@@ -26,6 +26,7 @@
 import com.google.devtools.build.lib.bazel.bzlmod.FakeRegistry;
 import com.google.devtools.build.lib.bazel.bzlmod.ModuleFileFunction;
 import com.google.devtools.build.lib.bazel.bzlmod.Version.ParseException;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
 import com.google.devtools.build.lib.skyframe.util.SkyframeExecutorTestUtils;
@@ -71,6 +72,17 @@
         getSkyframeExecutor().getDifferencerForTesting(), ImmutableList.of(registry.getUrl()));
   }
 
+  public static RepositoryMappingValue withMapping(
+      ImmutableMap<RepositoryName, RepositoryName> repositoryMapping) {
+    return RepositoryMappingValue.withMapping(RepositoryMapping.create(repositoryMapping));
+  }
+
+  public static RepositoryMappingValue withMappingAllowingFallback(
+      ImmutableMap<RepositoryName, RepositoryName> repositoryMapping) {
+    return RepositoryMappingValue.withMapping(
+        RepositoryMapping.createAllowingFallback(repositoryMapping));
+  }
+
   @Test
   public void testSimpleMapping() throws Exception {
     scratch.overwriteFile(
@@ -89,7 +101,7 @@
     assertThatEvaluationResult(result)
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(
                     RepositoryName.create("@a"),
                     RepositoryName.create("@b"),
@@ -113,7 +125,7 @@
     assertThatEvaluationResult(result)
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMapping(
                 ImmutableMap.of(
                     RepositoryName.create("@com_foo_bar_b"), RepositoryName.create("@B.1.0"))));
   }
@@ -140,7 +152,7 @@
     assertThatEvaluationResult(result)
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMapping(
                 ImmutableMap.of(
                     RepositoryName.create("@com_foo_bar_b"), RepositoryName.create("@B.1.0"))));
   }
@@ -162,8 +174,7 @@
     assertThatEvaluationResult(result)
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
-                ImmutableMap.of(RepositoryName.create("@A"), RepositoryName.create("@"))));
+            withMapping(ImmutableMap.of(RepositoryName.create("@A"), RepositoryName.create("@"))));
   }
 
   @Test
@@ -188,10 +199,12 @@
     assertThatEvaluationResult(result)
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMapping(
                 ImmutableMap.of(
-                    RepositoryName.create("@B1"), RepositoryName.create("@B.1.0"),
-                    RepositoryName.create("@B2"), RepositoryName.create("@B.2.0"))));
+                    RepositoryName.create("@B1"),
+                    RepositoryName.create("@B.1.0"),
+                    RepositoryName.create("@B2"),
+                    RepositoryName.create("@B.2.0"))));
   }
 
   @Test
@@ -222,9 +235,8 @@
     assertThatEvaluationResult(result)
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
-                ImmutableMap.of(
-                    RepositoryName.create("@D"), RepositoryName.create("@D.1.0"))));
+            withMapping(
+                ImmutableMap.of(RepositoryName.create("@D"), RepositoryName.create("@D.1.0"))));
   }
 
   @Test
@@ -253,7 +265,7 @@
     assertThatEvaluationResult(result)
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMapping(
                 ImmutableMap.of(
                     RepositoryName.create("@com_foo_bar_c"), RepositoryName.create("@C.1.0"))));
   }
@@ -281,7 +293,7 @@
     assertThatEvaluationResult(eval(skyKey1))
         .hasEntryThat(skyKey1)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(
                     RepositoryName.create("@a"),
                     RepositoryName.create("@b"),
@@ -290,7 +302,7 @@
     assertThatEvaluationResult(eval(skyKey2))
         .hasEntryThat(skyKey2)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(
                     RepositoryName.create("@x"),
                     RepositoryName.create("@y"),
@@ -314,7 +326,7 @@
     assertThatEvaluationResult(eval(skyKey))
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(
                     RepositoryName.create("@a"),
                     RepositoryName.create("@b"),
@@ -360,7 +372,7 @@
     assertThatEvaluationResult(eval(skyKey))
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.<RepositoryName, RepositoryName>builder()
                     .put(RepositoryName.create("@root"), RepositoryName.MAIN)
                     // mappings to @B get remapped to @B.1.0 because of module B@1.0
@@ -413,7 +425,7 @@
     assertThatEvaluationResult(eval(skyKey))
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(
                     RepositoryName.createFromValidStrippedName(TestConstants.WORKSPACE_NAME),
                     RepositoryName.MAIN)));
@@ -434,7 +446,7 @@
     assertThatEvaluationResult(eval(skyKey))
         .hasEntryThat(skyKey)
         .isEqualTo(
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(RepositoryName.create("@good"), RepositoryName.MAIN)));
   }
 
@@ -442,14 +454,14 @@
   public void testEqualsAndHashCode() throws Exception {
     new EqualsTester()
         .addEqualityGroup(
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(RepositoryName.create("@foo"), RepositoryName.create("@bar"))),
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(RepositoryName.create("@foo"), RepositoryName.create("@bar"))))
         .addEqualityGroup(
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(RepositoryName.create("@fizz"), RepositoryName.create("@buzz"))),
-            RepositoryMappingValue.withMapping(
+            withMappingAllowingFallback(
                 ImmutableMap.of(RepositoryName.create("@fizz"), RepositoryName.create("@buzz"))))
         .testEquals();
   }
diff --git a/src/test/java/com/google/devtools/build/lib/starlark/util/BazelEvaluationTestCase.java b/src/test/java/com/google/devtools/build/lib/starlark/util/BazelEvaluationTestCase.java
index 088ef64..7ee391b 100644
--- a/src/test/java/com/google/devtools/build/lib/starlark/util/BazelEvaluationTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/starlark/util/BazelEvaluationTestCase.java
@@ -19,6 +19,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.starlark.StarlarkModules;
 import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventCollector;
 import com.google.devtools.build.lib.events.EventKind;
@@ -127,7 +128,7 @@
             BazelStarlarkContext.Phase.LOADING,
             TestConstants.TOOLS_REPOSITORY,
             /*fragmentNameToClass=*/ null,
-            /*repoMapping=*/ ImmutableMap.of(),
+            /*repoMapping=*/ RepositoryMapping.ALWAYS_FALLBACK,
             /*convertedLabelsInPackage=*/ new HashMap<>(),
             new SymbolGenerator<>(new Object()),
             /*analysisRuleLabel=*/ null,