diff --git a/mpy-cross/main.c b/mpy-cross/main.c
index 246390383a..38190671c6 100644
--- a/mpy-cross/main.c
+++ b/mpy-cross/main.c
@@ -34,6 +34,7 @@
 #include "py/persistentcode.h"
 #include "py/runtime.h"
 #include "py/gc.h"
+#include "py/parsenum.h"
 #include "genhdr/mpversion.h"
 #ifdef _WIN32
 #include "ports/windows/fmode.h"
@@ -144,7 +145,7 @@ static int usage(char **argv) {
         "-march=<arch> : set architecture for native emitter;\n"
         "                x86, x64, armv6, armv6m, armv7m, armv7em, armv7emsp,\n"
         "                armv7emdp, xtensa, xtensawin, rv32imc, rv64imc, host, debug\n"
-        "-march-flags=<flags> : set architecture-specific flags\n"
+        "-march-flags=<flags> : set architecture-specific flags (can be either a dec/hex/bin value or a string)\n"
         "                       supported flags for rv32imc: zba\n"
         "\n"
         "Implementation specific options:\n", argv[0]
@@ -226,6 +227,38 @@ static char *backslash_to_forwardslash(char *path) {
     return path;
 }
 
+// This will need to be reworked in case mpy-cross needs to set more bits than
+// what its small int representation allows to fit in there.
+static bool parse_integer(const char *value, mp_uint_t *integer) {
+    assert(value && "Attempting to parse a NULL string");
+    assert(integer && "Attempting to store into a NULL integer buffer");
+
+    size_t value_length = strlen(value);
+    int base = 10;
+    if (value_length > 2 && value[0] == '0') {
+        if ((value[1] | 0x20) == 'b') {
+            base = 2;
+        } else if ((value[1] | 0x20) == 'x') {
+            base = 16;
+        } else {
+            return false;
+        }
+    }
+
+    bool valid = false;
+    nlr_buf_t nlr;
+    if (nlr_push(&nlr) == 0) {
+        mp_obj_t parsed = mp_parse_num_integer(value, value_length, base, NULL);
+        if (mp_obj_is_small_int(parsed)) {
+            *integer = MP_OBJ_SMALL_INT_VALUE(parsed);
+            valid = true;
+        }
+        nlr_pop();
+    }
+
+    return valid;
+}
+
 MP_NOINLINE int main_(int argc, char **argv) {
     pre_process_options(argc, argv);
 
@@ -378,7 +411,13 @@ MP_NOINLINE int main_(int argc, char **argv) {
         #if MICROPY_EMIT_NATIVE && MICROPY_EMIT_RV32
         if (mp_dynamic_compiler.native_arch == MP_NATIVE_ARCH_RV32IMC) {
             mp_dynamic_compiler.backend_options = (void *)&rv32_options;
-            if (strncmp(arch_flags, "zba", sizeof("zba") - 1) == 0) {
+            mp_uint_t raw_flags = 0;
+            if (parse_integer(arch_flags, &raw_flags)) {
+                if ((raw_flags & ~((mp_uint_t)RV32_EXT_ALL)) == 0) {
+                    rv32_options.allowed_extensions = raw_flags;
+                    processed = true;
+                }
+            } else if (strncmp(arch_flags, "zba", sizeof("zba") - 1) == 0) {
                 rv32_options.allowed_extensions |= RV32_EXT_ZBA;
                 processed = true;
             }