diff --git a/winpr/libwinpr/library/library.c b/winpr/libwinpr/library/library.c
index 8d21eb919..9ccbb7211 100644
--- a/winpr/libwinpr/library/library.c
+++ b/winpr/libwinpr/library/library.c
@@ -299,65 +299,92 @@ static DWORD module_from_proc(const char* proc, LPSTR lpFilename, DWORD nSize)
 
 DWORD GetModuleFileNameA(HMODULE hModule, LPSTR lpFilename, DWORD nSize)
 {
+	if (hModule)
+	{
+		WLog_ERR(TAG, "is not implemented");
+		SetLastError(ERROR_CALL_NOT_IMPLEMENTED);
+		return 0;
+	}
+
 #if defined(__linux__)
-	if (!hModule)
-		return module_from_proc("/proc/self/exe", lpFilename, nSize);
+	return module_from_proc("/proc/self/exe", lpFilename, nSize);
 #elif defined(__FreeBSD__)
 	int mib[] = { CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1 };
 	size_t cb = nSize;
 
-	const int rc = sysctl(mib, ARRAYSIZE(mib), lpFilename, &cb, NULL, 0);
-	if ((rc != 0) || (cb > nSize))
+	{
+		const int rc = sysctl(mib, ARRAYSIZE(mib), NULL, &cb, NULL, 0);
+		if (rc != 0)
+		{
+			SetLastError(ERROR_INTERNAL_ERROR);
+			return 0;
+		}
+	}
+
+	char* fullname = calloc(cb + 1, sizeof(char));
+	if (!fullname)
 	{
 		SetLastError(ERROR_INTERNAL_ERROR);
 		return 0;
 	}
 
-	return (DWORD)cb;
-#elif defined(__NetBSD__)
-	if (!hModule)
-		return module_from_proc("/proc/curproc/exe", lpFilename, nSize);
-#elif defined(__DragonFly__)
-	if (!hModule)
-		return module_from_proc("/proc/curproc/file", lpFilename, nSize);
-#elif defined(__MACOSX__)
-	int status;
-	size_t length;
-
-	if (!hModule)
 	{
-		char path[4096];
-		char buffer[4096];
-		uint32_t size = sizeof(path);
-		status = _NSGetExecutablePath(path, &size);
-
-		if (status != 0)
+		size_t cb2 = cb;
+		const int rc = sysctl(mib, ARRAYSIZE(mib), fullname, &cb2, NULL, 0);
+		if ((rc != 0) || (cb2 != cb))
 		{
-			/* path too small */
 			SetLastError(ERROR_INTERNAL_ERROR);
+			free(fullname);
 			return 0;
 		}
-
-		/*
-		 * _NSGetExecutablePath may not return the canonical path,
-		 * so use realpath to find the absolute, canonical path.
-		 */
-		realpath(path, buffer);
-		length = strnlen(buffer, sizeof(buffer));
-
-		if (length < nSize)
-		{
-			CopyMemory(lpFilename, buffer, length);
-			lpFilename[length] = '\0';
-			return (DWORD)length;
-		}
-
-		CopyMemory(lpFilename, buffer, nSize - 1);
-		lpFilename[nSize - 1] = '\0';
-		SetLastError(ERROR_INSUFFICIENT_BUFFER);
-		return nSize;
 	}
 
+	if (nSize > 0)
+	{
+		strncpy(lpFilename, fullname, nSize - 1);
+		lpFilename[nSize - 1] = '\0';
+	}
+	free(fullname);
+
+	if (nSize < cb)
+		SetLastError(ERROR_INSUFFICIENT_BUFFER);
+
+	return (DWORD)MIN(nSize, cb);
+#elif defined(__NetBSD__)
+	return module_from_proc("/proc/curproc/exe", lpFilename, nSize);
+#elif defined(__DragonFly__)
+	return module_from_proc("/proc/curproc/file", lpFilename, nSize);
+#elif defined(__MACOSX__)
+	char path[4096] = { 0 };
+	char buffer[4096] = { 0 };
+	uint32_t size = sizeof(path);
+	const int status = _NSGetExecutablePath(path, &size);
+
+	if (status != 0)
+	{
+		/* path too small */
+		SetLastError(ERROR_INTERNAL_ERROR);
+		return 0;
+	}
+
+	/*
+	 * _NSGetExecutablePath may not return the canonical path,
+	 * so use realpath to find the absolute, canonical path.
+	 */
+	realpath(path, buffer);
+	const size_t length = strnlen(buffer, sizeof(buffer));
+
+	if (length < nSize)
+	{
+		CopyMemory(lpFilename, buffer, length);
+		lpFilename[length] = '\0';
+		return (DWORD)length;
+	}
+
+	CopyMemory(lpFilename, buffer, nSize - 1);
+	lpFilename[nSize - 1] = '\0';
+	SetLastError(ERROR_INSUFFICIENT_BUFFER);
+	return nSize;
 #endif
 	WLog_ERR(TAG, "is not implemented");
 	SetLastError(ERROR_CALL_NOT_IMPLEMENTED);