diff --git a/pack.c b/pack.c
index 327c478af8..45b816a590 100644
--- a/pack.c
+++ b/pack.c
@@ -1011,10 +1011,11 @@ hex2num(char c)
 	rb_ary_store(ary, RARRAY_LEN(ary)+tmp_len-1, Qnil); \
 } while (0)
 
-/* Workaround for Oracle Solaris Studio 12.4/12.5 C compiler optimization bug
+/* Workaround for Oracle Developer Studio (Oracle Solaris Studio)
+ * 12.4/12.5/12.6 C compiler optimization bug
  * with "-xO4" optimization option.
  */
-#if defined(__SUNPRO_C) && 0x5130 <= __SUNPRO_C && __SUNPRO_C <= 0x5140
+#if defined(__SUNPRO_C) && 0x5130 <= __SUNPRO_C && __SUNPRO_C <= 0x5150
 # define AVOID_CC_BUG volatile
 #else
 # define AVOID_CC_BUG