diff --git a/src/material/tabs/tab-group.ts b/src/material/tabs/tab-group.ts
index c115e03fb612..e719fca94dd7 100644
--- a/src/material/tabs/tab-group.ts
+++ b/src/material/tabs/tab-group.ts
@@ -420,7 +420,7 @@ export abstract class _MatTabGroupBase extends _MatTabGroupMixinBase implements
   static ngAcceptInputType_animationDuration: NumberInput;
   static ngAcceptInputType_selectedIndex: NumberInput;
   static ngAcceptInputType_disableRipple: BooleanInput;
-  static ngAcceptInputType_contentTabIndex: BooleanInput;
+  static ngAcceptInputType_contentTabIndex: NumberInput;
 }
 
 /**
diff --git a/tools/public_api_guard/material/tabs.md b/tools/public_api_guard/material/tabs.md
index 3307cec79123..b4dcaf4fbe6b 100644
--- a/tools/public_api_guard/material/tabs.md
+++ b/tools/public_api_guard/material/tabs.md
@@ -244,7 +244,7 @@ export abstract class _MatTabGroupBase extends _MatTabGroupMixinBase implements
     // (undocumented)
     static ngAcceptInputType_animationDuration: NumberInput;
     // (undocumented)
-    static ngAcceptInputType_contentTabIndex: BooleanInput;
+    static ngAcceptInputType_contentTabIndex: NumberInput;
     // (undocumented)
     static ngAcceptInputType_disableRipple: BooleanInput;
     // (undocumented)