diff --git a/esphome/components/dallas_temp/dallas_temp.cpp b/esphome/components/dallas_temp/dallas_temp.cpp
index 13f2fa59bd7..f119e28e78e 100644
--- a/esphome/components/dallas_temp/dallas_temp.cpp
+++ b/esphome/components/dallas_temp/dallas_temp.cpp
@@ -136,6 +136,9 @@ bool DallasTemperatureSensor::check_scratch_pad_() {
 float DallasTemperatureSensor::get_temp_c_() {
   int16_t temp = (this->scratch_pad_[1] << 8) | this->scratch_pad_[0];
   if ((this->address_ & 0xff) == DALLAS_MODEL_DS18S20) {
+    if (this->scratch_pad_[7] == 0) {
+      return NAN;
+    }
     return (temp >> 1) + (this->scratch_pad_[7] - this->scratch_pad_[6]) / float(this->scratch_pad_[7]) - 0.25;
   }
   switch (this->resolution_) {
diff --git a/esphome/components/gpio/one_wire/gpio_one_wire.cpp b/esphome/components/gpio/one_wire/gpio_one_wire.cpp
index 4191c45de15..4e2a306fc94 100644
--- a/esphome/components/gpio/one_wire/gpio_one_wire.cpp
+++ b/esphome/components/gpio/one_wire/gpio_one_wire.cpp
@@ -131,7 +131,7 @@ uint8_t IRAM_ATTR GPIOOneWireBus::read8() {
 uint64_t IRAM_ATTR GPIOOneWireBus::read64() {
   InterruptLock lock;
   uint64_t ret = 0;
-  for (uint8_t i = 0; i < 8; i++) {
+  for (uint8_t i = 0; i < 64; i++) {
     ret |= (uint64_t(this->read_bit_()) << i);
   }
   return ret;