diff --git a/.appveyor.yml b/.appveyor.yml
index a9b296e0..93070f5f 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -41,6 +41,7 @@ before_build:
   - ren "C:\Program Files\Git\usr\bin\sh.exe" _sh.exe
 
 build_script:
+  - cl cpucount.cpp && .\cpucount.exe
   - md build && cd build
   - cmake -G "%CMAKE_GENERATOR%" %CMAKE_FLAGS% ..
   - if %compiler%==mingw ( mingw32-make tester examples )
diff --git a/cpucount.cpp b/cpucount.cpp
new file mode 100644
index 00000000..1dad1dd7
--- /dev/null
+++ b/cpucount.cpp
@@ -0,0 +1,68 @@
+// 17 may 2018
+#define UNICODE
+#define _UNICODE
+#define STRICT
+#define STRICT_TYPED_ITEMIDS
+#define WINVER			0x0600	/* from Microsoft's winnls.h */
+#define _WIN32_WINNT		0x0600
+#define _WIN32_WINDOWS	0x0600	/* from Microsoft's pdh.h */
+#define _WIN32_IE			0x0700
+#define NTDDI_VERSION		0x06000000
+#include <windows.h>
+#include <psapi.h>
+#include <stdio.h>
+
+int affinityCount(DWORD_PTR a)
+{
+	int n = 0;
+
+	while (a != 0) {
+		if ((a & 1) != 0)
+			n++;
+		a >>= 1;
+	}
+	return n;
+}
+
+int main(void)
+{
+	HANDLE pseudoCurrent, current;
+	DWORD_PTR pa, sa;
+	SYSTEM_INFO si;
+	DWORD le;
+
+	pseudoCurrent = GetCurrentProcess();
+	if (GetProcessAffinityMask(pseudoCurrent, &pa, &sa) != 0) {
+		printf("GetProcessAffinityMask(GetCurrentProcess()):\n");
+		printf("\tProcess - %d\n", affinityCount(pa));
+		printf("\tSystem  - %d\n", affinityCount(sa));
+	} else {
+		le = GetLastError();
+		fprintf(stderr, "error calling GetProcessAffinity(GetCurrentProcess()): %I32d\n", le);
+	}
+
+	if (DuplicateHandle(pseudoCurrent, pseudoCurrent,
+		pseudoCurrent, &current,
+		0, FALSE, DUPLICATE_SAME_ACCESS) != 0)
+		if (GetProcessAffinityMask(current, &pa, &sa) != 0) {
+			printf("GetProcessAffinityMask(real handle):\n");
+			printf("\tProcess - %d\n", affinityCount(pa));
+			printf("\tSystem  - %d\n", affinityCount(sa));
+		} else {
+			le = GetLastError();
+			fprintf(stderr, "error calling GetProcessAffinity(real handle): %I32d\n", le);
+		}
+	else {
+		le = GetLastError();
+		fprintf(stderr, "error calling DuplicateHandle(GetCurrentProcess()) (no real handle info available): %I32d\n", le);
+	}
+
+	ZeroMemory(&si, sizeof (SYSTEM_INFO));
+	GetSystemInfo(&si);
+	printf("GetSystemInfo() processor count: %I32d\n", si.dwNumberOfProcessors);
+	ZeroMemory(&si, sizeof (SYSTEM_INFO));
+	GetNativeSystemInfo(&si);
+	printf("GetNativeSystemInfo() processor count: %I32d\n", si.dwNumberOfProcessors);
+
+	return 0;
+}