diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 01967d09..56be9516 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -40,6 +40,10 @@ add_library( exiv2lib_int OBJECT
     unused.h
 )
 
+if (COMPILER_IS_GCC OR COMPILER_IS_CLANG)
+  set_source_files_properties(http.cpp PROPERTIES COMPILE_FLAGS -fno-sanitize=address,undefined)
+endif()
+
 add_library( exiv2lib
     ../include/exiv2/config.h
     ../include/exiv2/exiv2.hpp
diff --git a/src/basicio.cpp b/src/basicio.cpp
index b5ec43c8..12174616 100644
--- a/src/basicio.cpp
+++ b/src/basicio.cpp
@@ -1960,8 +1960,9 @@ namespace Exiv2 {
             for ( size_t block = 0 ; block < blocks ; block ++ ) {
                 void* p = p_->blocksMap_[block].getData();
                 if  ( p ) {
-                    nRealData += blockSize ;
-                    memcpy(bigBlock_+(block*blockSize),p,blockSize);
+                    size_t nRead = block==(blocks-1)?p_->size_-nRealData:blockSize;
+                    memcpy(bigBlock_+(block*blockSize),p,nRead);
+                    nRealData   += nRead ;
                 }
             }
 #ifdef EXIV2_DEBUG_MESSAGES