diff a/src/hotspot/cpu/ppc/relocInfo_ppc.hpp b/src/hotspot/cpu/ppc/relocInfo_ppc.hpp
--- a/src/hotspot/cpu/ppc/relocInfo_ppc.hpp
+++ b/src/hotspot/cpu/ppc/relocInfo_ppc.hpp
@@ -38,11 +38,12 @@
 #ifndef _LP64
     format_width       =  0
 #else
     // Except narrow oops in 64-bits VM.
     // Must be at least 2 for ZGC GC barrier patching.
-    format_width       =  2
+    // Must be at least 3 for Shenandoah GC barrier patching.
+    format_width       =  3
 #endif
   };
 
  public: