diff --git a/source/cpu_id.cc b/source/cpu_id.cc
index 535c4e9e9..8ad35acb1 100644
--- a/source/cpu_id.cc
+++ b/source/cpu_id.cc
@@ -53,6 +53,11 @@ extern "C" {
 #define SAFEBUFFERS
 #endif
 
+#if defined(_MSC_VER)
+// MSVC provides strtok_s which is functionally equivalent to strtok_r.
+#define strtok_r strtok_s
+#endif
+
 // cpu_info_ variable for SIMD instruction sets detected.
 LIBYUV_API int cpu_info_ = 0;
 
@@ -330,16 +335,17 @@ LIBYUV_API SAFEBUFFERS int RiscvCpuCaps(const char* cpuinfo_name) {
         // supervisor-level extensions.
         extensions = strpbrk(isa, "zxs");
         if (extensions) {
+          extensions_len = strlen(extensions);
           // Multi-letter extensions are seperated by a single underscore
           // as described in RISC-V User-Level ISA V2.2.
-          char* ext = strtok(extensions, "_");
-          extensions_len = strlen(extensions);
+          char* saveptr = NULL;
+          char* ext = strtok_r(extensions, "_", &saveptr);
           while (ext) {
             // Search for the ZVFH (Vector FP16) extension.
             if (!strcmp(ext, "zvfh")) {
               flag |= kCpuHasRVVZVFH;
             }
-            ext = strtok(NULL, "_");
+            ext = strtok_r(NULL, "_", &saveptr);
           }
         }
         std_isa_len = isa_len - extensions_len - 5;