diff --git a/src/os/win32/sigar_os.h b/src/os/win32/sigar_os.h
index e35f38f1..8eda061e 100644
--- a/src/os/win32/sigar_os.h
+++ b/src/os/win32/sigar_os.h
@@ -43,7 +43,7 @@
 /* see apr/include/arch/win32/atime.h */
 #define EPOCH_DELTA INT64_C(11644473600000000)
 
-#define SIGAR_CMDLINE_MAX 4096
+#define SIGAR_CMDLINE_MAX 4096<<2
 
 /* XXX: support CP_UTF8 ? */
 
diff --git a/src/os/win32/wmi.cpp b/src/os/win32/wmi.cpp
index a68b5348..bc1019d6 100644
--- a/src/os/win32/wmi.cpp
+++ b/src/os/win32/wmi.cpp
@@ -28,7 +28,7 @@
 #pragma comment(lib, "wbemuuid.lib")
 
 #ifndef SIGAR_CMDLINE_MAX
-#define SIGAR_CMDLINE_MAX 4096
+#define SIGAR_CMDLINE_MAX 4096<<2
 #endif
 
 class WMI {