diff --git a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceGlobals.java b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceGlobals.java
index 719873637f382f..ab98b38f460358 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceGlobals.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceGlobals.java
@@ -49,8 +49,8 @@
 /** A collection of global Starlark build API functions that apply to WORKSPACE files. */
 public class WorkspaceGlobals implements WorkspaceGlobalsApi {
 
-  // Must start with a letter and can contain letters, numbers, and underscores
-  private static final Pattern LEGAL_WORKSPACE_NAME = Pattern.compile("^\\p{Alpha}\\w*$");
+  // Must start with a letter and can contain letters, numbers, underscores and hyphens.
+  private static final Pattern LEGAL_WORKSPACE_NAME = Pattern.compile("^\\p{Alpha}[\\w-]*$");
 
   private final boolean allowOverride;
   private final RuleFactory ruleFactory;