diff --git a/src/server/core/core-read-op.cpp b/src/server/core/core-read-op.cpp
index 765344475a8a71949bcfdd29c77c5b0b8fd7ecbf..a8dcd64e26fac0b54dc6e4d898da58475e140b5d 100644
--- a/src/server/core/core-read-op.cpp
+++ b/src/server/core/core-read-op.cpp
@@ -196,12 +196,10 @@ void read_op_exec_read(void* u, uint64_t offset, size_t len, buffer_u buf, size_
 
                 case seg_type_t::ZERO:
                     coverage.set(seg.start_index, seg.end_index);
-                    if(*bytes_read < seg.end_index) *bytes_read = seg.end_index;
                     break;
 
                 case seg_type_t::TOMBSTONE:
                     coverage.set(seg.start_index, seg.end_index);
-                    if(*bytes_read < seg.start_index) *bytes_read = seg.start_index;
                     break;
 
                 case seg_type_t::BAKE_REGION: {
@@ -218,7 +216,6 @@ void read_op_exec_read(void* u, uint64_t offset, size_t len, buffer_u buf, size_
                             LEAVING;
                             return;
                         }
-                        if(*bytes_read < r.end) *bytes_read = r.end;
                     }
                     break;
                 } // end case seg_type_t::BAKE_REGION
@@ -258,7 +255,6 @@ void read_op_exec_read(void* u, uint64_t offset, size_t len, buffer_u buf, size_
                             LEAVING;
                             return;
                         } // end if
-                        if(*bytes_read < r.end) *bytes_read = r.end;
                     } // end for
                 } // end case seg_type_t::SMALL_REGION
 
@@ -267,6 +263,7 @@ void read_op_exec_read(void* u, uint64_t offset, size_t len, buffer_u buf, size_
 
         if(num_segments != max_segments) done = true;
     }
+    *bytes_read = coverage.bytes_read();
     LEAVING;
 }
 
diff --git a/src/server/core/covermap.hpp b/src/server/core/covermap.hpp
index b4a0369e59861e91c13c2206725346b6f4d237f7..1fbd070681a67bb3d053a5c7c90f93f14a954a04 100644
--- a/src/server/core/covermap.hpp
+++ b/src/server/core/covermap.hpp
@@ -37,13 +37,15 @@ class covermap {
     };
 
     covermap(T s, T e)
-        : m_start(s), m_end(e) {}
+        : m_start(s), m_end(e), m_level(0) {}
 
     std::list<segment> set(T start, T end) {
         // make start and end match the bounds
         if(start < m_start) start = m_start;
         if(end > m_end) end = m_end;
 
+        if(end-start == 0) return std::list<segment>();
+
         std::list<segment> result;
         // easy case: the coverage map is empty
         if(m_segments.empty()) {
@@ -115,6 +117,18 @@ class covermap {
     bool full() const {
         return capacity() == level();
     }
+
+    uint64_t bytes_read() const {
+        if(full()) return capacity();
+        if(m_segments.empty()) return 0;
+        uint64_t start = m_end;
+        uint64_t end   = m_start;
+        for(const auto& s : m_segments) {
+            if(s.first < start) start = s.first;
+            if(s.second > end)  end = s.second;
+        }
+        return end-start;
+    }
 };
 
 #endif