diff --git a/src/p_w64pep.cpp b/src/p_w64pep.cpp
index 3a8adb4e..5ef28833 100644
--- a/src/p_w64pep.cpp
+++ b/src/p_w64pep.cpp
@@ -266,6 +266,11 @@ void PackW64Pep::defineSymbols(unsigned ncsection, unsigned upxsection,
     linker->defineSymbol("START", upxsection);
 }
 
+void PackW64Pep::setOhHeaderSize(const pe_section_t *osection)
+{
+    oh.headersize = ALIGN_UP(pe_offset + sizeof(oh) + sizeof(*osection) * oh.objects, oh.filealign);
+}
+
 void PackW64Pep::pack(OutputFile *fo)
 {
     super::pack0(fo
diff --git a/src/p_w64pep.h b/src/p_w64pep.h
index cf1b409b..aac38156 100644
--- a/src/p_w64pep.h
+++ b/src/p_w64pep.h
@@ -51,7 +51,7 @@ public:
                                unsigned sizeof_oh, unsigned isize_isplit,
                                unsigned s1addr);
     virtual void setOhDataBase(const pe_section_t *) {}
-    virtual void setOhHeaderSize(const pe_section_t *) {}
+    virtual void setOhHeaderSize(const pe_section_t *osection);
     virtual void pack(OutputFile *fo);
 
     virtual bool canPack();