diff --git a/src/p_armpe.cpp b/src/p_armpe.cpp
index 20bc5fa9..c81f9c8f 100644
--- a/src/p_armpe.cpp
+++ b/src/p_armpe.cpp
@@ -247,7 +247,7 @@ void PackArmPe::setOhHeaderSize(const pe_section_t *osection)
 
 void PackArmPe::pack(OutputFile *fo)
 {
-    super::pack0(fo, 1U << 9, 0x10000, true);
+    super::pack0(fo, (1u<<IMAGE_SUBSYSTEM_WINDOWS_CE_GUI), 0x10000, true);
 }
 
 /* vim:set ts=4 sw=4 et: */
diff --git a/src/p_w32pe.cpp b/src/p_w32pe.cpp
index 74819521..d8686e14 100644
--- a/src/p_w32pe.cpp
+++ b/src/p_w32pe.cpp
@@ -283,7 +283,12 @@ void PackW32Pe::setOhHeaderSize(const pe_section_t *osection)
 
 void PackW32Pe::pack(OutputFile *fo)
 {
-    super::pack0(fo, 0x0c, 0x400000, false);
+    super::pack0(fo
+        , (1u<<IMAGE_SUBSYSTEM_WINDOWS_GUI)
+        | (1u<<IMAGE_SUBSYSTEM_WINDOWS_CUI)
+        | (1u<<IMAGE_SUBSYSTEM_EFI_APPLICATION)  // no decompressor yet
+        , 0x400000
+        , false);
 }
 
 /* vim:set ts=4 sw=4 et: */
diff --git a/src/p_w64pep.cpp b/src/p_w64pep.cpp
index 2d90d742..3a8adb4e 100644
--- a/src/p_w64pep.cpp
+++ b/src/p_w64pep.cpp
@@ -268,7 +268,11 @@ void PackW64Pep::defineSymbols(unsigned ncsection, unsigned upxsection,
 
 void PackW64Pep::pack(OutputFile *fo)
 {
-    super::pack0(fo, 0x0c, 0x0000000140000000ULL);
+    super::pack0(fo
+        , (1u<<IMAGE_SUBSYSTEM_WINDOWS_GUI)
+        | (1u<<IMAGE_SUBSYSTEM_WINDOWS_CUI)
+        | (1u<<IMAGE_SUBSYSTEM_EFI_APPLICATION)  // no decompressor yet
+        , 0x0000000140000000ULL);
 }
 
 /* vim:set ts=4 sw=4 et: */
diff --git a/src/pefile.cpp b/src/pefile.cpp
index b50c1c0b..1007f237 100644
--- a/src/pefile.cpp
+++ b/src/pefile.cpp
@@ -2148,6 +2148,16 @@ void PeFile::checkHeaderValues(unsigned subsystem, unsigned mask,
                      subsystem);
         throwCantPack(buf);
     }
+    if (mask & (
+             (1u<<IMAGE_SUBSYSTEM_EFI_APPLICATION)
+            |(1u<<IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER)
+            |(1u<<IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER)
+            |(1u<<IMAGE_SUBSYSTEM_EFI_ROM)
+              ))
+    {
+        infoWarning("PE: subsystem %u (EFI) lacks a run-time decompressor",
+            subsystem);
+    }
     //check CLR Runtime Header directory entry
     if (IDSIZE(PEDIR_COMRT))
         throwCantPack(".NET files are not yet supported");
diff --git a/src/pefile.h b/src/pefile.h
index 0232d4bd..ce97741b 100644
--- a/src/pefile.h
+++ b/src/pefile.h
@@ -282,6 +282,22 @@ protected:
         IMAGE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE = 0x8000
     };
 
+    enum {
+        IMAGE_SUBSYSTEM_UNKNOWN = 0,
+        IMAGE_SUBSYSTEM_NATIVE  = 1,
+        IMAGE_SUBSYSTEM_WINDOWS_GUI  = 2,  // Grapical
+        IMAGE_SUBSYSTEM_WINDOWS_CUI  = 3,  // Character-mode
+        IMAGE_SUBSYSTEM_WINDOWS_OS2_CUI  = 5,
+        IMAGE_SUBSYSTEM_WINDOWS_POSIX_CUI  = 7,
+        IMAGE_SUBSYSTEM_WINDOWS_CE_GUI  = 9,
+        IMAGE_SUBSYSTEM_EFI_APPLICATION  = 10,
+        IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER  = 11,
+        IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER  = 12,
+        IMAGE_SUBSYSTEM_EFI_ROM  = 13,
+        IMAGE_SUBSYSTEM_XBOX  = 14,
+        IMAGE_SUBSYSTEM_WINDOWS_BOOT_APPLICATION  = 16
+    };
+
     // predefined resource types
     enum {
         RT_CURSOR = 1, RT_BITMAP, RT_ICON, RT_MENU, RT_DIALOG, RT_STRING,