Fix setting INCLUDE_SIGN0=0
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3e0562d..5cc477a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -35,6 +35,11 @@
 option (include_sign1    "Include COSE_SIGN1" ON)
 option (include_sign0    "Include COSE_SIGN1" ON)
 
+if (NOT include_sign0)
+   message ( "Use include_sign1 rather than include_sign0" )
+   set (include_sign1 ${include_sign0})
+endif ()
+
 set ( dist_dir          ${CMAKE_BINARY_DIR}/dist )
 set ( prefix            ${CMAKE_INSTALL_PREFIX} )
 set ( exec_prefix       ${CMAKE_INSTALL_PREFIX}/bin )
@@ -67,8 +72,8 @@
 if (NOT include_sign)
    add_definitions( -DINCLUDE_SIGN=0 )
 endif ()
-if (NOT include_sign0 AND NOT include_sign1)
-   add_definitions( -DINCLUDE_SIGN0=0 )
+if (NOT include_sign1)
+   add_definitions( -DINCLUDE_SIGN1=0 )
 endif ()
 
 if ( MSVC OR CMAKE_C_COMPILER_ID MATCHES "Clang" )