diff --git a/include/fast_float/float_common.h b/include/fast_float/float_common.h
index 8791709..bcff7e1 100644
--- a/include/fast_float/float_common.h
+++ b/include/fast_float/float_common.h
@@ -6,11 +6,13 @@
 #include <cassert>
 
 #if (defined(__i386) || defined(__i386__) || defined(_M_IX86)   \
-     || defined(__arm__) || defined(__MINGW32__))
+     || defined(__arm__)                                        \
+     || defined(__MINGW32__))
 #define FASTFLOAT_32BIT
 #elif (defined(__x86_64) || defined(__x86_64__) || defined(_M_X64)   \
        || defined(__amd64) || defined(__aarch64__) || defined(_M_ARM64) \
-       || defined(__MINGW64__))
+       || defined(__MINGW64__)                                          \
+       || defined(__s390x__))
 #define FASTFLOAT_64BIT
 #else
 #error Unknown platform