diff --git a/base/shell/cmd/cmd.h b/base/shell/cmd/cmd.h
index 48f6df0b5b2..20f946463ca 100644
--- a/base/shell/cmd/cmd.h
+++ b/base/shell/cmd/cmd.h
@@ -165,7 +165,11 @@ INT  CommandEchoerr (LPTSTR);
 INT  CommandEchoserr (LPTSTR);
 
 /* Prototypes for ERROR.C */
-VOID ErrorMessage (DWORD, LPTSTR, ...);
+VOID
+ErrorMessage(
+    IN DWORD dwErrorCode,
+    IN LPTSTR szFormat OPTIONAL,
+    ...);
 
 VOID error_no_pipe (VOID);
 VOID error_bad_command (LPTSTR);
diff --git a/base/shell/cmd/del.c b/base/shell/cmd/del.c
index 7f2d2a63db6..8e5cfbdccb8 100644
--- a/base/shell/cmd/del.c
+++ b/base/shell/cmd/del.c
@@ -263,7 +263,7 @@ DeleteFiles(LPTSTR FileName, DWORD* dwFlags, DWORD dwAttrFlags)
             }
             else
             {
-                ErrorMessage (GetLastError(), _T(""));
+                ErrorMessage (GetLastError(), NULL);
 //              FindClose(hFile);
 //              return -1;
             }
diff --git a/base/shell/cmd/error.c b/base/shell/cmd/error.c
index 92f08a0d996..c0f61fd00a7 100644
--- a/base/shell/cmd/error.c
+++ b/base/shell/cmd/error.c
@@ -22,19 +22,23 @@
 
 #include "precomp.h"
 
-
-VOID ErrorMessage (DWORD dwErrorCode, LPTSTR szFormat, ...)
+VOID
+ErrorMessage(
+    IN DWORD dwErrorCode,
+    IN LPTSTR szFormat OPTIONAL,
+    ...)
 {
-    TCHAR szMsg[RC_STRING_MAX_SIZE];
-    TCHAR  szMessage[1024];
-    LPTSTR szError;
     va_list arg_ptr;
+    LPTSTR szError;
+    TCHAR szMsg[RC_STRING_MAX_SIZE];
+    TCHAR szMessage[1024];
 
     if (dwErrorCode == ERROR_SUCCESS)
         return;
 
     nErrorLevel = 1;
 
+    *szMessage = 0;
     if (szFormat)
     {
         va_start(arg_ptr, szFormat);
@@ -48,7 +52,7 @@ VOID ErrorMessage (DWORD dwErrorCode, LPTSTR szFormat, ...)
     {
         ConErrPrintf(_T("%s %s\n"), szError, szMessage);
         if (szError)
-            LocalFree (szError);
+            LocalFree(szError);
         return;
     }
 
diff --git a/base/shell/cmd/vol.c b/base/shell/cmd/vol.c
index eed27c9dd57..cdd529e6376 100644
--- a/base/shell/cmd/vol.c
+++ b/base/shell/cmd/vol.c
@@ -41,7 +41,7 @@ PrintVolumeHeader (LPTSTR pszRootPath)
                              NULL,
                              0))
     {
-        ErrorMessage(GetLastError (), _T(""));
+        ErrorMessage(GetLastError (), NULL);
         return 1;
     }