diff --git a/src/backend/utils/mmgr/freepage.c b/src/backend/utils/mmgr/freepage.c
index b26a295a4e..dcf246faf1 100644
--- a/src/backend/utils/mmgr/freepage.c
+++ b/src/backend/utils/mmgr/freepage.c
@@ -434,7 +434,7 @@ FreePageManagerDump(FreePageManager *fpm)
 
 	/* Dump general stuff. */
 	appendStringInfo(&buf, "metadata: self %zu max contiguous pages = %zu\n",
-					 fpm->self.relptr_off, fpm->contiguous_pages);
+					 relptr_offset(fpm->self), fpm->contiguous_pages);
 
 	/* Dump btree. */
 	if (fpm->btree_depth > 0)
@@ -1269,7 +1269,7 @@ FreePageManagerDumpBtree(FreePageManager *fpm, FreePageBtree *btp,
 		if (btp->hdr.magic == FREE_PAGE_INTERNAL_MAGIC)
 			appendStringInfo(buf, " %zu->%zu",
 							 btp->u.internal_key[index].first_page,
-							 btp->u.internal_key[index].child.relptr_off / FPM_PAGE_SIZE);
+							 relptr_offset(btp->u.internal_key[index].child) / FPM_PAGE_SIZE);
 		else
 			appendStringInfo(buf, " %zu(%zu)",
 							 btp->u.leaf_key[index].first_page,
@@ -1859,7 +1859,7 @@ FreePagePopSpanLeader(FreePageManager *fpm, Size pageno)
 	{
 		Size		f = Min(span->npages, FPM_NUM_FREELISTS) - 1;
 
-		Assert(fpm->freelist[f].relptr_off == pageno * FPM_PAGE_SIZE);
+		Assert(relptr_offset(fpm->freelist[f]) == pageno * FPM_PAGE_SIZE);
 		relptr_copy(fpm->freelist[f], span->next);
 	}
 }
diff --git a/src/include/utils/freepage.h b/src/include/utils/freepage.h
index 08064b10f9..e69b2804ec 100644
--- a/src/include/utils/freepage.h
+++ b/src/include/utils/freepage.h
@@ -78,11 +78,11 @@ struct FreePageManager
 #define fpm_pointer_is_page_aligned(base, ptr)		\
 	(((Size) (((char *) (ptr)) - (base))) % FPM_PAGE_SIZE == 0)
 #define fpm_relptr_is_page_aligned(base, relptr)		\
-	((relptr).relptr_off % FPM_PAGE_SIZE == 0)
+	(relptr_offset(relptr) % FPM_PAGE_SIZE == 0)
 
 /* Macro to find base address of the segment containing a FreePageManager. */
 #define fpm_segment_base(fpm)	\
-	(((char *) fpm) - fpm->self.relptr_off)
+	(((char *) fpm) - relptr_offset(fpm->self))
 
 /* Macro to access a FreePageManager's largest consecutive run of pages. */
 #define fpm_largest(fpm) \
diff --git a/src/include/utils/relptr.h b/src/include/utils/relptr.h
index cc80a7200d..9364dd6694 100644
--- a/src/include/utils/relptr.h
+++ b/src/include/utils/relptr.h
@@ -42,7 +42,7 @@
 #define relptr_access(base, rp) \
 	(AssertVariableIsOfTypeMacro(base, char *), \
 	 (__typeof__((rp).relptr_type)) ((rp).relptr_off == 0 ? NULL : \
-		(base + (rp).relptr_off)))
+		(base) + (rp).relptr_off - 1))
 #else
 /*
  * If we don't have __builtin_types_compatible_p, assume we might not have
@@ -50,12 +50,15 @@
  */
 #define relptr_access(base, rp) \
 	(AssertVariableIsOfTypeMacro(base, char *), \
-	 (void *) ((rp).relptr_off == 0 ? NULL : (base + (rp).relptr_off)))
+	 (void *) ((rp).relptr_off == 0 ? NULL : (base) + (rp).relptr_off - 1))
 #endif
 
 #define relptr_is_null(rp) \
 	((rp).relptr_off == 0)
 
+#define relptr_offset(rp) \
+	((rp).relptr_off - 1)
+
 /* We use this inline to avoid double eval of "val" in relptr_store */
 static inline Size
 relptr_store_eval(char *base, char *val)
@@ -64,8 +67,8 @@ relptr_store_eval(char *base, char *val)
 		return 0;
 	else
 	{
-		Assert(val > base);
-		return val - base;
+		Assert(val >= base);
+		return val - base + 1;
 	}
 }
 
@@ -73,7 +76,7 @@ relptr_store_eval(char *base, char *val)
 #define relptr_store(base, rp, val) \
 	(AssertVariableIsOfTypeMacro(base, char *), \
 	 AssertVariableIsOfTypeMacro(val, __typeof__((rp).relptr_type)), \
-	 (rp).relptr_off = relptr_store_eval(base, (char *) (val)))
+	 (rp).relptr_off = relptr_store_eval((base), (char *) (val)))
 #else
 /*
  * If we don't have __builtin_types_compatible_p, assume we might not have
@@ -81,7 +84,7 @@ relptr_store_eval(char *base, char *val)
  */
 #define relptr_store(base, rp, val) \
 	(AssertVariableIsOfTypeMacro(base, char *), \
-	 (rp).relptr_off = relptr_store_eval(base, (char *) (val)))
+	 (rp).relptr_off = relptr_store_eval((base), (char *) (val)))
 #endif
 
 #define relptr_copy(rp1, rp2) \