diff --git a/dlls/dbghelp/elf_module.c b/dlls/dbghelp/elf_module.c
index e4c6e448152..e18c9effeb3 100644
--- a/dlls/dbghelp/elf_module.c
+++ b/dlls/dbghelp/elf_module.c
@@ -324,6 +324,7 @@ static BOOL elf_map_file(struct elf_map_file_data* emfd, struct image_file_map*
 #else
     if (fmap->u.elf.elfhdr.e_ident[EI_CLASS] != ELFCLASS32) goto done;
 #endif
+    fmap->addr_size = fmap->u.elf.elfhdr.e_ident[EI_CLASS] == ELFCLASS64 ? 64 : 32;
     fmap->u.elf.sect = HeapAlloc(GetProcessHeap(), 0,
                                  fmap->u.elf.elfhdr.e_shnum * sizeof(fmap->u.elf.sect[0]));
     if (!fmap->u.elf.sect) goto done;
diff --git a/dlls/dbghelp/image_private.h b/dlls/dbghelp/image_private.h
index 2642f281548..2afed79b8a6 100644
--- a/dlls/dbghelp/image_private.h
+++ b/dlls/dbghelp/image_private.h
@@ -74,6 +74,7 @@
 struct image_file_map
 {
     enum module_type            modtype;
+    unsigned                    addr_size;      /* either 16 (not used), 32 or 64 */
     union
     {
         struct elf_file_map
diff --git a/dlls/dbghelp/pe_module.c b/dlls/dbghelp/pe_module.c
index 79a4d90a29c..f43d9711781 100644
--- a/dlls/dbghelp/pe_module.c
+++ b/dlls/dbghelp/pe_module.c
@@ -224,6 +224,12 @@ static BOOL pe_map_file(HANDLE file, struct image_file_map* fmap, enum module_ty
 
             if (!(nthdr = RtlImageNtHeader(mapping))) goto error;
             memcpy(&fmap->u.pe.ntheader, nthdr, sizeof(fmap->u.pe.ntheader));
+            switch (nthdr->OptionalHeader.Magic)
+            {
+            case 0x10b: fmap->addr_size = 32; break;
+            case 0x20b: fmap->addr_size = 64; break;
+            default: return FALSE;
+            }
             section = (IMAGE_SECTION_HEADER*)
                 ((char*)&nthdr->OptionalHeader + nthdr->FileHeader.SizeOfOptionalHeader);
             fmap->u.pe.sect = HeapAlloc(GetProcessHeap(), 0,