diff --git a/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java b/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java
index 3211834b677d88..0b28c8635390e1 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java
@@ -455,7 +455,7 @@ public class StarlarkSemanticsOptions extends OptionsBase implements Serializabl
 
   @Option(
       name = "incompatible_disallow_unverified_http_downloads",
-      defaultValue = "false",
+      defaultValue = "true",
       documentationCategory = OptionDocumentationCategory.STARLARK_SEMANTICS,
       effectTags = {OptionEffectTag.LOADING_AND_ANALYSIS},
       metadataTags = {
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java b/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java
index 9860f6f86bae0d..9865368bd63ecd 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java
@@ -278,7 +278,7 @@ public static Builder builderWithDefaults() {
           .incompatibleDisallowOldStyleArgsAdd(true)
           .incompatibleDisallowRuleExecutionPlatformConstraintsAllowed(false)
           .incompatibleDisallowStructProviderSyntax(false)
-          .incompatibleDisallowUnverifiedHttpDownloads(false)
+          .incompatibleDisallowUnverifiedHttpDownloads(true)
           .incompatibleExpandDirectories(true)
           .incompatibleNewActionsApi(true)
           .incompatibleNoAttrLicense(true)