diff -Nru mayo-0.9.0+ds/debian/changelog mayo-0.9.0+ds/debian/changelog
--- mayo-0.9.0+ds/debian/changelog	2025-04-17 18:40:45.000000000 +0800
+++ mayo-0.9.0+ds/debian/changelog	2025-04-26 22:47:05.000000000 +0800
@@ -1,3 +1,9 @@
+mayo (0.9.0+ds-2.1) UNRELEASED; urgency=medium
+
+  * fix unknown platform on riscv. 
+
+ -- Gui-Yue <yuemeng.gui@gmail.com>  Sat, 26 Apr 2025 22:47:05 +0800
+
 mayo (0.9.0+ds-2) unstable; urgency=medium
 
   * Apply patch: src/3rdparty/fast_float/float_common.h:
diff -Nru mayo-0.9.0+ds/debian/patches/fix_unknown_platform.patch mayo-0.9.0+ds/debian/patches/fix_unknown_platform.patch
--- mayo-0.9.0+ds/debian/patches/fix_unknown_platform.patch	1970-01-01 08:00:00.000000000 +0800
+++ mayo-0.9.0+ds/debian/patches/fix_unknown_platform.patch	2025-04-26 22:47:05.000000000 +0800
@@ -0,0 +1,18 @@
+--- a/src/3rdparty/fast_float/float_common.h
++++ b/src/3rdparty/fast_float/float_common.h
+@@ -11,11 +11,13 @@
+        || defined(__s390x__)                                            \
+        || (defined(__ppc64__) || defined(__PPC64__) || defined(__ppc64le__) || defined(__PPC64LE__)) \
+        || defined(__EMSCRIPTEN__) \
+-       || defined(__loongarch_lp64))
++       || defined(__loongarch_lp64) \
++       || (defined(__riscv) && __riscv_xlen == 64))
+ #define FASTFLOAT_64BIT
+ #elif (defined(__i386) || defined(__i386__) || defined(_M_IX86)   \
+      || defined(__arm__)                                        \
+-     || defined(__MINGW32__))
++     || defined(__MINGW32__) \
++     || (defined(__riscv) && __riscv_xlen == 32))
+ #define FASTFLOAT_32BIT
+ #else
+ #error Unknown platform (not 32-bit, not 64-bit?)
diff -Nru mayo-0.9.0+ds/debian/patches/series mayo-0.9.0+ds/debian/patches/series
--- mayo-0.9.0+ds/debian/patches/series	2025-04-17 18:40:45.000000000 +0800
+++ mayo-0.9.0+ds/debian/patches/series	2025-04-26 22:44:21.000000000 +0800
@@ -1,2 +1,3 @@
 yes
 fastfloat-loongarch
+fix_unknown_platform.patch