diff --git a/sys/arm64/include/ofw_machdep.h b/sys/arm64/include/ofw_machdep.h
index e9c65ef02801..511fc8d71c19 100644
--- a/sys/arm64/include/ofw_machdep.h
+++ b/sys/arm64/include/ofw_machdep.h
@@ -41,7 +41,4 @@ struct mem_region {
 	vm_size_t	mr_size;
 };
 
-/* FDT follows ePAPR */
-#define	OFW_EPAPR
-
 #endif /* _MACHINE_OFW_MACHDEP_H_ */
diff --git a/sys/dev/ofw/ofw_bus_subr.c b/sys/dev/ofw/ofw_bus_subr.c
index c286373940d4..60a341c538ee 100644
--- a/sys/dev/ofw/ofw_bus_subr.c
+++ b/sys/dev/ofw/ofw_bus_subr.c
@@ -361,10 +361,11 @@ ofw_bus_search_intrmap(void *intr, int intrsz, void *regs, int physsz,
 	paddrsz = 0;
 	while (i > 0) {
 		bcopy(mptr + physsz + intrsz, &parent, sizeof(parent));
-#ifdef OFW_EPAPR
+#ifndef OFW_IMAP_NO_IPARENT_ADDR_CELLS
 		/*
-		 * Find if we need to read the parent address data. Sparc64
-		 * uses a different encoding that doesn't include this data.
+		 * Find if we need to read the parent address data.
+		 * CHRP-derived OF bindings, including ePAPR-compliant FDTs,
+		 * use this as an optional part of the specifier.
 		 */
 		if (OF_getencprop(OF_node_from_xref(parent),
 		    "#address-cells", &paddrsz, sizeof(paddrsz)) == -1)
diff --git a/sys/sparc64/include/ofw_machdep.h b/sys/sparc64/include/ofw_machdep.h
index bc69b3b3773c..fcacc10d446d 100644
--- a/sys/sparc64/include/ofw_machdep.h
+++ b/sys/sparc64/include/ofw_machdep.h
@@ -34,6 +34,9 @@
 
 typedef uint64_t cell_t;
 
+/* sparc64 doesn't use the interrupt parent #address-cells in interrupt maps */
+#define OFW_IMAP_NO_IPARENT_ADDR_CELLS
+
 int  OF_decode_addr(phandle_t, int, int *, bus_addr_t *);
 void OF_getetheraddr(device_t, u_char *);
 u_int OF_getscsinitid(device_t);