diff --git a/build_tools/build_detect_platform b/build_tools/build_detect_platform
index 1d89cba79..7aa079a36 100755
--- a/build_tools/build_detect_platform
+++ b/build_tools/build_detect_platform
@@ -638,6 +638,9 @@ if test "0$PORTABLE" -eq 0; then
       COMMON_FLAGS="$COMMON_FLAGS -march=z196 "
     fi
     COMMON_FLAGS="$COMMON_FLAGS"
+  elif test -n "`echo $TARGET_ARCHITECTURE | grep ^riscv64`"; then
+    RISC_ISA=$(cat /proc/cpuinfo | grep isa | head -1 | cut --delimiter=: -f 2 | cut -b 2-)
+    COMMON_FLAGS="$COMMON_FLAGS -march=${RISC_ISA}"
   elif [ "$TARGET_OS" == "IOS" ]; then
     COMMON_FLAGS="$COMMON_FLAGS"
   elif [ "$TARGET_OS" == "AIX" ] || [ "$TARGET_OS" == "SunOS" ]; then
@@ -658,6 +661,11 @@ else
     COMMON_FLAGS="$COMMON_FLAGS -march=z196 "
   fi
 
+  if test -n "`echo $TARGET_ARCHITECTURE | grep ^riscv64`"; then
+    RISC_ISA=$(cat /proc/cpuinfo | grep isa | head -1 | cut --delimiter=: -f 2 | cut -b 2-)
+    COMMON_FLAGS="$COMMON_FLAGS -march=${RISC_ISA}"
+  fi
+
   if [[ "${PLATFORM}" == "OS_MACOSX" ]]; then
     # For portability compile for macOS 10.12 (2016) or newer
     COMMON_FLAGS="$COMMON_FLAGS -mmacosx-version-min=10.12"