diff --git a/src/p_w32pe_i386.cpp b/src/p_w32pe_i386.cpp
index 646bdcbd..89abf6f0 100644
--- a/src/p_w32pe_i386.cpp
+++ b/src/p_w32pe_i386.cpp
@@ -76,7 +76,10 @@ int PackW32PeI386::readFileHeader() {
 **************************************************************************/
 
 bool PackW32PeI386::canPack() {
-    if (!readFileHeader() || ih.cpu < IMAGE_FILE_MACHINE_I386 || ih.cpu > 0x150)
+    if (!readFileHeader())
+        return false;
+    checkMachine(ih.cpu);
+    if (ih.cpu < IMAGE_FILE_MACHINE_I386 || ih.cpu > 0x150)
         return false;
     return true;
 }
diff --git a/src/p_w64pe_amd64.cpp b/src/p_w64pe_amd64.cpp
index 486e33cc..2d5a5d87 100644
--- a/src/p_w64pe_amd64.cpp
+++ b/src/p_w64pe_amd64.cpp
@@ -66,8 +66,10 @@ Linker *PackW64PeAmd64::newLinker() const { return new ElfLinkerAMD64; }
 **************************************************************************/
 
 bool PackW64PeAmd64::canPack() {
-    // just check if machine type is 0x8664
-    if (!readFileHeader() || ih.cpu != IMAGE_FILE_MACHINE_AMD64)
+    if (!readFileHeader())
+        return false;
+    checkMachine(ih.cpu);
+    if (ih.cpu != IMAGE_FILE_MACHINE_AMD64)
         return false;
     return true;
 }
diff --git a/src/p_w64pe_arm64.cpp b/src/p_w64pe_arm64.cpp
index 920e4b34..7f005a5f 100644
--- a/src/p_w64pe_arm64.cpp
+++ b/src/p_w64pe_arm64.cpp
@@ -60,7 +60,10 @@ const int *PackW64PeArm64::getFilters() const { return nullptr; }
 **************************************************************************/
 
 bool PackW64PeArm64::canPack() {
-    if (!readFileHeader() || ih.cpu != IMAGE_FILE_MACHINE_ARM64)
+    if (!readFileHeader())
+        return false;
+    checkMachine(ih.cpu);
+    if (ih.cpu != IMAGE_FILE_MACHINE_ARM64)
         return false;
     throwCantPack("not yet implemented");
     return true;
diff --git a/src/p_wince_arm.cpp b/src/p_wince_arm.cpp
index f4d97eff..d8d0042a 100644
--- a/src/p_wince_arm.cpp
+++ b/src/p_wince_arm.cpp
@@ -114,6 +114,7 @@ void PackWinCeArm::processTls(Interval *) // pass 1
 bool PackWinCeArm::canPack() {
     if (!readFileHeader())
         return false;
+    checkMachine(ih.cpu);
     if (ih.cpu != IMAGE_FILE_MACHINE_ARM && ih.cpu != IMAGE_FILE_MACHINE_THUMB)
         return false;
     use_thumb_stub |= ih.cpu == IMAGE_FILE_MACHINE_THUMB || (ih.entry & 1) == 1;
diff --git a/src/packmast.cpp b/src/packmast.cpp
index 4fa7d61e..3e9d75fb 100644
--- a/src/packmast.cpp
+++ b/src/packmast.cpp
@@ -158,12 +158,12 @@ Packer *PackMaster::visitAllPackers(visit_func_t func, InputFile *f, const optio
         D(PackDjgpp2);
         D(PackTmt);
         D(PackWcle);
+        // D(PackW64PeArm64EC); // NOT YET IMPLEMENTED
+        // D(PackW64PeArm64); // NOT YET IMPLEMENTED
         D(PackW64PeAmd64);
         D(PackW32PeI386);
     }
     D(PackWinCeArm);
-    // D(PackW64PeArm64EC); // NOT YET IMPLEMENTED
-    // D(PackW64PeArm64); // NOT YET IMPLEMENTED
     D(PackExe);
 
     //
diff --git a/src/pefile.cpp b/src/pefile.cpp
index 31f1df00..16878347 100644
--- a/src/pefile.cpp
+++ b/src/pefile.cpp
@@ -117,6 +117,34 @@ bool PeFile::testUnpackVersion(int version) const {
 // util
 **************************************************************************/
 
+// early check of machine to generate a helpful error message
+// FIXME/TODO: proper check for ARM64EC
+// FIXME/TODO: proper check for ARM64X "universal" binary
+// CHPE   Compiled Hybrid PE: Microsoft internal only?
+// CHPEV2 Compiled Hybrid PE: ARM64EC, ARM64X
+/*static*/ int PeFile::checkMachine(unsigned cpu) {
+    // known but not supported
+    if (cpu == IMAGE_FILE_MACHINE_ARMNT)
+        throwCantPack("win32/arm32 is not supported"); // obsolete
+    if (cpu == IMAGE_FILE_MACHINE_ARM64)
+        throwCantPack("win64/arm64 is not supported");
+    // FIXME: it seems that arm64ec actually uses MACHINE_AMD64 ???
+    if (cpu == IMAGE_FILE_MACHINE_ARM64EC)
+        throwCantPack("win64/arm64ec is not supported");
+
+    // supported
+    if (cpu == IMAGE_FILE_MACHINE_AMD64)
+        return UPX_F_W64PE_AMD64;
+    if (cpu == IMAGE_FILE_MACHINE_ARM || cpu == IMAGE_FILE_MACHINE_THUMB)
+        return UPX_F_WINCE_ARM;
+    if (cpu >= IMAGE_FILE_MACHINE_I386 && cpu <= 0x150) // what is this 0x150 ???
+        return UPX_F_W32PE_I386;
+
+    // other or unkown (alpha, mips, etc.)
+    throwCantPack("pefile: unsupported machine %#x", cpu);
+    return 0; // pacify msvc
+}
+
 int PeFile::readFileHeader() {
     struct alignas(1) exe_header_t {
         LE16 mz;
diff --git a/src/pefile.h b/src/pefile.h
index 22c51735..383dbaff 100644
--- a/src/pefile.h
+++ b/src/pefile.h
@@ -82,6 +82,7 @@ protected:
     int canUnpack0(unsigned max_sections, unsigned objs, unsigned ih_entry, unsigned ih_size);
 
 protected:
+    static int checkMachine(unsigned cpu);
     virtual int readFileHeader();
     virtual bool testUnpackVersion(int version) const override;
     virtual void readPeHeader() = 0;