diff --git a/Changes b/Changes
index 467fb4ea0..e928d1ea2 100644
--- a/Changes
+++ b/Changes
@@ -35,6 +35,7 @@ Verilator 4.215 devel
 * Fix $fopen etc on integer arrays (#3214). [adrienlemasle]
 * Fix $size on dynamic strings (#3216).
 * Fix %0 format on $value$plusargs (#3217).
+* Fix timescale portability on Arm64 (#3222).
 
 
 Verilator 4.214 2021-10-17
diff --git a/include/verilatedos.h b/include/verilatedos.h
index 9a1f50a75..b6a837663 100644
--- a/include/verilatedos.h
+++ b/include/verilatedos.h
@@ -333,7 +333,8 @@ typedef signed __int32 ssize_t;  ///< signed size_t; returned from read()
 # include <stdint.h>  // Linux and most flavors
 # include <sys/types.h>  // __WORDSIZE
 # include <unistd.h>  // ssize_t
-typedef char vlsint8_t;  ///< 8-bit signed type
+// Arm64 gcc 9.3.0 defaults to unsigned char, not signed char
+typedef signed char vlsint8_t;  ///< 8-bit signed type
 typedef uint8_t vluint8_t;  ///< 8-bit unsigned type
 typedef short vlsint16_t;  ///< 16-bit signed type
 typedef uint16_t vluint16_t;  ///< 16-bit unsigned type