diff --git a/libgimp/meson.build b/libgimp/meson.build
index 097af6a828..df774151c9 100644
--- a/libgimp/meson.build
+++ b/libgimp/meson.build
@@ -627,14 +627,9 @@ else
   endif
 endif
 
-if not platform_windows and not platform_osx
-  # Verify .def files for Windows.
-  # Ironically we only check this on non-Windows platform, since the
-  # script expects .so libraries, and I'm not sure that the `nm` tool is
-  # available on Windows.
-  # On the other hand, it is how it always has been, since we used to
-  # only run this on dist step (which we historically run on a GNU/Linux
-  # machine). And it worked fine until now.
+if not platform_osx and host_cpu_family != 'x86'
+  # Verify .def files for Windows linking.
+  # We check this on non-Windows platform (Debian) on CI, and on Windows itself.
   custom_target('check-def-files',
     input: [
       '../libgimpbase/gimpbase.def',
diff --git a/tools/defcheck.py b/tools/defcheck.py
index 4eb7766b26..352138549a 100755
--- a/tools/defcheck.py
+++ b/tools/defcheck.py
@@ -25,11 +25,11 @@ Invoke in the top level of the gimp source tree after compiling GIMP.
 If srcdir != builddir, run it in the build directory and pass the name
 of the source directory on the command-line.
 
-Needs the tool "nm" to work
+Needs the tool "objdump" to work
 
 """
 
-import sys, subprocess
+import os, sys, subprocess
 
 from os import path
 
@@ -54,10 +54,22 @@ if len(sys.argv) > 1:
       print("Directory '%s' does not exist" % srcdir)
       sys.exit (-1)
 
+libextension   = ".so"
+command        = "nm --defined-only --extern-only "
+platform_linux = True
+
+if sys.platform in ['win32', 'cygwin']:
+   libextension   = ".dll"
+   command        = "objdump -p "
+   platform_linux = False
+
 for df in def_files:
    directory, name = path.split (df)
    basename, extension = name.split (".")
-   libname = path.join(directory, "lib" + basename + "-*.so")
+
+   libname = path.join(directory, "lib" + basename + "-*" + libextension)
+   #FIXME: This leaks to ninja stdout, which should not happen
+   #print ("platform: " + sys.platform + " - extracting symbols from " + libname)
 
    filename = df
    if srcdir:
@@ -75,26 +87,46 @@ for df in def_files:
       if defsymbols[i] in defsymbols[:i]:
          doublesymbols.append ((defsymbols[i], i+2))
 
-   unsortindex = -1
+   sorterrors = ""
+   sortok = True
    for i in range (len (defsymbols)-1):
-      if defsymbols[i] > defsymbols[i+1]:
-         unsortindex = i+1
-         break;
+      if defsymbols[i].lower() > defsymbols[i+1].lower():
+         sorterrors += f"{defsymbols[i]} > {defsymbols[i+1]}\n"
+         sortok = False
+   sorterrors = sorterrors.split(sep='\n')
 
-   status, nm = subprocess.getstatusoutput ("nm --defined-only --extern-only " +
-                                            libname)
+   status, nm = subprocess.getstatusoutput (command + libname)
    if status != 0:
       print("trouble reading {} - has it been compiled?".format(libname))
       have_errors = -1
       continue
 
-   nmsymbols = nm.split()[2::3]
+   nmsymbols = ""
+   if platform_linux:
+      nmsymbols = nm
+
+   else: # Windows
+      # remove parts of objdump output we don't need: anything up to a few lines
+      # after Export Table: ' Ordinal      RVA  Name'
+
+      objnm = nm.split(sep='\n')
+
+      found = False
+      nmsymbols = ""
+      for s in objnm:
+         if s == " Ordinal      RVA  Name":
+            found = True
+         elif found:
+            nmsymbols += s
+         # else: skip this line
+
+   nmsymbols = nmsymbols.split()[2::3]
    nmsymbols = [s for s in nmsymbols if s[0] != '_']
 
-   missing_defs = [s for s in nmsymbols  if s not in defsymbols]
-   missing_nms  = [s for s in defsymbols if s not in nmsymbols]
+   missing_defs = [s for s in nmsymbols  if s not in defsymbols and s not in exclude_symbols]
+   missing_nms  = [s for s in defsymbols if s not in nmsymbols  and s not in exclude_symbols]
 
-   if unsortindex >= 0 or missing_defs or missing_nms or doublesymbols:
+   if missing_defs or missing_nms or doublesymbols or not sortok:
       print()
       print("Problem found in", filename)
 
@@ -118,9 +150,11 @@ for df in def_files:
             print("     : %s (line %d)" % s)
          print()
 
-      if unsortindex >= 0:
-         print("  the .def-file is not properly sorted (line %d)" % (unsortindex + 2))
-         print()
+      if not sortok:
+         print("  the .def-file is not properly sorted in the following cases")
+         for s in sorterrors:
+            if s != "":
+               print("     * ", s)
 
       have_errors = -1