diff --git a/artifacts/postprocess-binary.py b/artifacts/postprocess-binary.py
index 8d4b488..a59a48f 100644
--- a/artifacts/postprocess-binary.py
+++ b/artifacts/postprocess-binary.py
@@ -55,7 +55,9 @@ def library_symbols(file: Path) -> list[str]:
             if active:
                 if not line.strip():
                     return syms
-                syms.append(line.split()[2])
+                sym = line.split()[-1]
+                if sym != 'Name':
+                    syms.append(sym)
             elif 'Ordinal/Name Pointer' in line:
                 active = True
         raise Exception("Couldn't parse objdump output")
diff --git a/bintool b/bintool
index 7329903..d7453a2 100755
--- a/bintool
+++ b/bintool
@@ -50,7 +50,7 @@ from common.meson import (
 )
 from common.software import Project
 
-WINDOWS_API_VERS = (4,)
+WINDOWS_API_VERS = (4, 5)
 LINUX_API_VERS = (3,)
 # we have a higher minimum than the underlying meson.build
 MESON_MIN_VER = (1, 5, 0)
diff --git a/builder/windows/Dockerfile b/builder/windows/Dockerfile
index 62e8d56..b65dc8d 100644
--- a/builder/windows/Dockerfile
+++ b/builder/windows/Dockerfile
@@ -2,7 +2,7 @@ FROM docker.io/gentoo/stage3:latest
 # NOTE: try to keep the current container image compatible with the latest
 # stable source release, so people can conveniently build from the source
 # tarball
-RUN touch /etc/openslide-winbuild-builder-v{3,4}
+RUN touch /etc/openslide-winbuild-builder-v5
 RUN echo 'FEATURES="-sandbox -usersandbox -ipc-sandbox -network-sandbox -pid-sandbox"' >> /etc/portage/make.conf
 COPY package.accept_keywords /etc/portage/package.accept_keywords/openslide
 COPY package.use /etc/portage/package.use/openslide