diff --git a/ports/raspberrypi/common-hal/pulseio/PulseIn.c b/ports/raspberrypi/common-hal/pulseio/PulseIn.c
index cd78f6807f..78f05d5d63 100644
--- a/ports/raspberrypi/common-hal/pulseio/PulseIn.c
+++ b/ports/raspberrypi/common-hal/pulseio/PulseIn.c
@@ -142,8 +142,15 @@ void common_hal_pulseio_pulsein_interrupt() {
             // ignore pulses that are too short
             if (result <= MAX_PULSE && result > MIN_PULSE) {
                 self->buffer[buf_index] = (uint16_t)result;
-                buf_index++;
-                self->len++;
+                if (self->len < self->maxlen) {
+                    self->len++;
+                }
+                if (buf_index < self->maxlen) {
+                    buf_index++;
+                } else {
+                    self->start = 0;
+                    buf_index = 0;
+                }
             }
         }
     }
diff --git a/py/vm.c b/py/vm.c
index 17ac860e6e..e51c2e2165 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -127,11 +127,21 @@ mp_vm_return_kind_t PLACE_IN_ITCM(mp_execute_bytecode)(mp_code_state_t * code_st
     #endif
     #if MICROPY_OPT_COMPUTED_GOTO
     #include "py/vmentrytable.h"
+    #if MICROPY_OPT_COMPUTED_GOTO_SAVE_SPACE
+    #define ONE_TRUE_DISPATCH() one_true_dispatch : do { \
+        TRACE(ip); \
+        MARK_EXC_IP_GLOBAL(); \
+        goto *(void *)((char *) && entry_MP_BC_LOAD_CONST_FALSE + entry_table[*ip++]); \
+} while (0)
+    #define DISPATCH() do { goto one_true_dispatch; } while (0)
+    #else
+    #define ONE_TRUE_DISPATCH() DISPATCH()
     #define DISPATCH() do { \
         TRACE(ip); \
         MARK_EXC_IP_GLOBAL(); \
         goto *entry_table[*ip++]; \
 } while (0)
+    #endif
     #define DISPATCH_WITH_PEND_EXC_CHECK() goto pending_exception_check
     #define ENTRY(op) entry_##op
     #define ENTRY_DEFAULT entry_default
@@ -197,7 +207,7 @@ mp_vm_return_kind_t PLACE_IN_ITCM(mp_execute_bytecode)(mp_code_state_t * code_st
             for (;;) {
             dispatch_loop:
                 #if MICROPY_OPT_COMPUTED_GOTO
-                DISPATCH();
+                ONE_TRUE_DISPATCH();
                 #else
                 TRACE(ip);
                 MARK_EXC_IP_GLOBAL();