diff --git a/erlang/apps/lib/include/pdp10_elf36.hrl b/erlang/apps/lib/include/pdp10_elf36.hrl
index ddd28ec..a4f3112 100644
--- a/erlang/apps/lib/include/pdp10_elf36.hrl
+++ b/erlang/apps/lib/include/pdp10_elf36.hrl
@@ -1038,6 +1038,8 @@
         , p_align       :: elf36_Word() % Segment alignment, file & memory
         }).
 
+-define(ELF36_PHDR_SIZEOF, (8 * 4)).
+
 %% Values for program header, p_type field.
 
 -define(PT_NULL,        0).             % Program header table entry unused