platformio: section '.text' will not fit in region 'iram1_0_seg'

[datanizing]

Fantastic project, but I can't manage to compile it with PlatformIO:

$ platformio run

Processing d1_mini (platform: espressif8266; board: d1_mini; framework: arduino)
----------------------------------------------------------------------------------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/espressif8266/d1_mini.html
PLATFORM: Espressif 8266 (1.5.0) > WEMOS D1 mini
HARDWARE: ESP8266 80MHz, 80KB RAM, 4MB Flash
PACKAGES:
 - framework-arduinoespressif8266 1.20300.1 (2.3.0)
 - tool-esptool 1.409.0 (4.9)
 - toolchain-xtensa 1.40802.0 (4.8.2)
Converting esp8266-vindriktning-particle-sensor.ino
LDF: Library Dependency Finder -> http://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 26 compatible libraries
Scanning dependencies...
Dependency Graph
|-- <ArduinoJson> 6.18.3
|-- <PubSubClient> 2.8.0
|-- <WiFiManager> 0.16.0
|   |-- <DNSServer> 1.1.0
|   |   |-- <ESP8266WiFi> 1.0
|   |-- <ESP8266WebServer> 1.0
|   |   |-- <ESP8266WiFi> 1.0
|   |-- <ESP8266WiFi> 1.0
|-- <EspSoftwareSerial>
|-- <ArduinoOTA> 1.0
|   |-- <ESP8266WiFi> 1.0
|   |-- <ESP8266mDNS>
|   |   |-- <ESP8266WiFi> 1.0
|-- <DNSServer> 1.1.0
|   |-- <ESP8266WiFi> 1.0
|-- <ESP8266WebServer> 1.0
|   |-- <ESP8266WiFi> 1.0
|-- <ESP8266WiFi> 1.0
Building in release mode
Compiling .pio/build/d1_mini/src/esp8266-vindriktning-particle-sensor.ino.cpp.o
Linking .pio/build/d1_mini/firmware.elf
/PATH_TO_LD/ld: .pio/build/d1_mini/firmware.elf section `.text' will not fit in region `iram1_0_seg'
collect2: error: ld returned 1 exit status
*** [.pio/build/d1_mini/firmware.elf] Error 1

What could be wrong?