diff --git a/dlls/shlwapi/string.c b/dlls/shlwapi/string.c
index c65d576..e2f1cba 100644
--- a/dlls/shlwapi/string.c
+++ b/dlls/shlwapi/string.c
@@ -477,7 +477,8 @@ LPWSTR WINAPI StrCatW(LPWSTR lpszStr, LPCWSTR lpszSrc)
 {
   TRACE("(%s,%s)\n", debugstr_w(lpszStr), debugstr_w(lpszSrc));
 
-  strcatW(lpszStr, lpszSrc);
+  if (lpszStr && lpszSrc)
+    strcatW(lpszStr, lpszSrc);
   return lpszStr;
 }
 
@@ -497,7 +498,8 @@ LPWSTR WINAPI StrCpyW(LPWSTR lpszStr, LPCWSTR lpszSrc)
 {
   TRACE("(%p,%s)\n", lpszStr, debugstr_w(lpszSrc));
 
-  strcpyW(lpszStr, lpszSrc);
+  if (lpszStr && lpszSrc)
+    strcpyW(lpszStr, lpszSrc);
   return lpszStr;
 }
 
diff --git a/dlls/shlwapi/tests/string.c b/dlls/shlwapi/tests/string.c
index c918bcc..b23bf0b 100644
--- a/dlls/shlwapi/tests/string.c
+++ b/dlls/shlwapi/tests/string.c
@@ -407,16 +407,25 @@ static void test_StrCpyW(void)
   WCHAR szSrc[256];
   WCHAR szBuff[256];
   const StrFormatSizeResult* result = StrFormatSize_results;
-
+  LPWSTR lpRes;
 
   while(result->value)
   {
     MultiByteToWideChar(0,0,result->byte_size_64,-1,szSrc,sizeof(szSrc)/sizeof(WCHAR));
 
-    StrCpyW(szBuff, szSrc);
-    ok(!StrCmpW(szSrc, szBuff), "Copied string %s wrong\n", result->byte_size_64);
+    lpRes = StrCpyW(szBuff, szSrc);
+    ok(!StrCmpW(szSrc, szBuff) && lpRes == szBuff, "Copied string %s wrong\n", result->byte_size_64);
     result++;
   }
+
+  lpRes = StrCpyW(szBuff, NULL);
+  ok(lpRes == szBuff, "Wrong return value: got %p expected %p\n", lpRes, szBuff);
+
+  lpRes = StrCpyW(NULL, szSrc);
+  ok(lpRes == NULL, "Wrong return value: got %p expected NULL\n", lpRes);
+
+  lpRes = StrCpyW(NULL, NULL);
+  ok(lpRes == NULL, "Wrong return value: got %p expected NULL\n", lpRes);
 }
 
 static void test_StrChrNW(void)