diff --git a/dlls/usp10/usp10.c b/dlls/usp10/usp10.c
index fa4dc796a0e..f3fb36917f5 100644
--- a/dlls/usp10/usp10.c
+++ b/dlls/usp10/usp10.c
@@ -1477,7 +1477,8 @@ static HRESULT _ItemizeInternal(const WCHAR *pwcInChars, int cInChars,
         }
     }
 
-    while ((!levels || (levels && levels[cnt+1] == levels[0])) && (pwcInChars[cnt] == Numeric_space) && cnt < cInChars)
+    while ((!levels || (levels && cnt+1 < cInChars && levels[cnt+1] == levels[0]))
+            && (cnt < cInChars && pwcInChars[cnt] == Numeric_space))
         cnt++;
 
     if (cnt == cInChars) /* All Spaces */