diff --git a/cmake/fc.cmake b/cmake/fc.cmake
index b70c788c1..c496f6368 100644
--- a/cmake/fc.cmake
+++ b/cmake/fc.cmake
@@ -66,6 +66,13 @@ if (${F_COMPILER} STREQUAL "GFORTRAN" OR ${F_COMPILER} STREQUAL "F95" OR CMAKE_F
         set(FCOMMON_OPT "${FCOMMON_OPT} -mabi=lp32")
       endif ()
     endif ()
+    if (RISCV64)
+      if (BINARY64)
+        if (INTERFACE64)
+          set(FCOMMON_OPT "${FCOMMON_OPT} -fdefault-integer-8")
+        endif ()
+      endif ()
+    endif ()
   else ()
     if (BINARY64)
       set(FCOMMON_OPT "${FCOMMON_OPT} -m64")