3 files changed, 5 insertions, 3 deletions
diff --git a/op.h b/op.h
index f402d761cc..d00f74ff28 100644
--- a/op.h
+++ b/op.h
@@ -360,7 +360,7 @@ struct pmop {
 #define PM_SETRE(o,r)   ((o)->op_pmregexp = (r))
 #endif
 
-#define PMf_BASE_SHIFT _RXf_PMf_SHIFT
+#define PMf_BASE_SHIFT ((_RXf_PMf_SHIFT_NEXT)-1)
 
 /* taint $1 etc. if target tainted */
 #define PMf_RETAINT	(1<<(PMf_BASE_SHIFT+1))
diff --git a/op_reg_common.h b/op_reg_common.h
index b0fd273b3d..de100dc780 100644
--- a/op_reg_common.h
+++ b/op_reg_common.h
@@ -24,4 +24,6 @@
 #define RXf_PMf_LOCALE		(1 << 5)
 #define PMf_LOCALE		(1 << 5)
 
-#define _RXf_PMf_SHIFT 5    /* Begins with '_' so won't be exported by B */
+/* Next available bit after the above.  Name begins with '_' so won't be
+ * exported by B */
+#define _RXf_PMf_SHIFT_NEXT 6
diff --git a/regexp.h b/regexp.h
index ec897881e3..5246c1231e 100644
--- a/regexp.h
+++ b/regexp.h
@@ -291,7 +291,7 @@ and check for NULL.
  *
  */
 
-#define RXf_BASE_SHIFT _RXf_PMf_SHIFT
+#define RXf_BASE_SHIFT ((_RXf_PMf_SHIFT_NEXT)-1)
 
 /* Anchor and GPOS related stuff */
 #define RXf_ANCH_BOL    	(1<<(RXf_BASE_SHIFT+3))