diff --git a/web/utils/process-preconditions.go b/web/utils/process-preconditions.go
index 71b2810..99d2d31 100644
--- a/web/utils/process-preconditions.go
+++ b/web/utils/process-preconditions.go
@@ -37,6 +37,7 @@ func ProcessSupportedPreconditionsForNext(rw http.ResponseWriter, req *http.Requ
 		}
 		if conditionFailed {
 			SwitchToNonCachingHeaders(rw.Header())
+			rw.Header().Del("Content-Length")
 			WriteResponseHeaderCanWriteBody(req.Method, rw, http.StatusPreconditionFailed, "")
 			return false
 		}
@@ -54,6 +55,7 @@ func ProcessSupportedPreconditionsForNext(rw http.ResponseWriter, req *http.Requ
 		parse, err := time.Parse(http.TimeFormat, req.Header.Get("If-Unmodified-Since"))
 		if err == nil && modT.After(parse) {
 			SwitchToNonCachingHeaders(rw.Header())
+			rw.Header().Del("Content-Length")
 			WriteResponseHeaderCanWriteBody(req.Method, rw, http.StatusPreconditionFailed, "")
 			return false
 		}
@@ -99,6 +101,7 @@ func ProcessRangePreconditions(maxLength int64, rw http.ResponseWriter, req *htt
 			}
 		} else {
 			SwitchToNonCachingHeaders(rw.Header())
+			rw.Header().Del("Content-Length")
 			rw.Header().Set("Content-Range", "bytes */"+strconv.FormatInt(maxLength, 10))
 			WriteResponseHeaderCanWriteBody(req.Method, rw, http.StatusRequestedRangeNotSatisfiable, "")
 			return nil