diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index afbf66b9d..7fc211491 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -132,7 +132,7 @@ size_t FdSource::readUnbuffered(char * data, size_t len)
         n = ::read(fd, data, len);
     } while (n == -1 && errno == EINTR);
     if (n == -1) { _good = false; throw SysError("reading from file"); }
-    if (n == 0) { _good = false; throw EndOfFile(endOfFileError); }
+    if (n == 0) { _good = false; throw EndOfFile(std::string(*endOfFileError)); }
     read += n;
     return n;
 }
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index 689b2070b..d9522566f 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -153,7 +153,7 @@ struct FdSource : BufferedSource
 {
     int fd;
     size_t read = 0;
-    std::string endOfFileError{"unexpected end-of-file"};
+    BackedStringView endOfFileError{"unexpected end-of-file"};
 
     FdSource() : fd(-1) { }
     FdSource(int fd) : fd(fd) { }