diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,11 @@
+arduino-copilot (1.7.9) upstream; urgency=medium
+
+  * Update to copilot-4.3.
+  * Copilot has a =: operator now. Since =: is a core arduino-copilot
+    operator, the one from copilot is not re-exported by Copilot.Arduino.
+
+ -- Joey Hess <id@joeyh.name>  Wed, 19 Mar 2025 14:27:06 -0400
+
 arduino-copilot (1.7.8) upstream; urgency=medium
 
   * Update to copilot-3.18.1.
diff --git a/Examples/Blink/stack.yaml b/Examples/Blink/stack.yaml
--- a/Examples/Blink/stack.yaml
+++ b/Examples/Blink/stack.yaml
@@ -3,15 +3,15 @@
 - '../..'
 resolver: lts-22.11
 extra-deps:
-- sketch-frp-copilot-1.0.10
-- copilot-3.18.1
-- copilot-c99-3.18.1
-- copilot-core-3.18.1
-- copilot-language-3.18.1
-- copilot-libraries-3.18.1
-- copilot-theorem-3.18.1
-- copilot-interpreter-3.18.1
-- copilot-prettyprinter-3.18.1
+- sketch-frp-copilot-1.0.11
+- copilot-4.3
+- copilot-c99-4.3
+- copilot-core-4.3
+- copilot-language-4.3
+- copilot-libraries-4.3
+- copilot-theorem-4.3
+- copilot-interpreter-4.3
+- copilot-prettyprinter-4.3
 - language-c99-0.2.0
 - language-c99-simple-0.3.0
 - language-c99-util-0.2.0
diff --git a/Examples/Button/stack.yaml b/Examples/Button/stack.yaml
--- a/Examples/Button/stack.yaml
+++ b/Examples/Button/stack.yaml
@@ -3,15 +3,15 @@
 - '../..'
 resolver: lts-22.11
 extra-deps:
-- sketch-frp-copilot-1.0.10
-- copilot-3.18.1
-- copilot-c99-3.18.1
-- copilot-core-3.18.1
-- copilot-language-3.18.1
-- copilot-libraries-3.18.1
-- copilot-theorem-3.18.1
-- copilot-interpreter-3.18.1
-- copilot-prettyprinter-3.18.1
+  - sketch-frp-copilot-1.0.11
+- copilot-4.3
+- copilot-c99-4.3
+- copilot-core-4.3
+- copilot-language-4.3
+- copilot-libraries-4.3
+- copilot-theorem-4.3
+- copilot-interpreter-4.3
+- copilot-prettyprinter-4.3
 - language-c99-0.2.0
 - language-c99-simple-0.3.0
 - language-c99-util-0.2.0
diff --git a/Examples/ButtonHold/stack.yaml b/Examples/ButtonHold/stack.yaml
--- a/Examples/ButtonHold/stack.yaml
+++ b/Examples/ButtonHold/stack.yaml
@@ -3,15 +3,15 @@
 - '../..'
 resolver: lts-22.11
 extra-deps:
-- sketch-frp-copilot-1.0.10
-- copilot-3.18.1
-- copilot-c99-3.18.1
-- copilot-core-3.18.1
-- copilot-language-3.18.1
-- copilot-libraries-3.18.1
-- copilot-theorem-3.18.1
-- copilot-interpreter-3.18.1
-- copilot-prettyprinter-3.18.1
+- sketch-frp-copilot-1.0.11
+- copilot-4.3
+- copilot-c99-4.3
+- copilot-core-4.3
+- copilot-language-4.3
+- copilot-libraries-4.3
+- copilot-theorem-4.3
+- copilot-interpreter-4.3
+- copilot-prettyprinter-4.3
 - language-c99-0.2.0
 - language-c99-simple-0.3.0
 - language-c99-util-0.2.0
diff --git a/Examples/EEPROM/stack.yaml b/Examples/EEPROM/stack.yaml
--- a/Examples/EEPROM/stack.yaml
+++ b/Examples/EEPROM/stack.yaml
@@ -3,15 +3,15 @@
 - '../..'
 resolver: lts-22.11
 extra-deps: 
-- sketch-frp-copilot-1.0.10
-- copilot-3.18.1
-- copilot-c99-3.18.1
-- copilot-core-3.18.1
-- copilot-language-3.18.1
-- copilot-libraries-3.18.1
-- copilot-theorem-3.18.1
-- copilot-interpreter-3.18.1
-- copilot-prettyprinter-3.18.1
+- sketch-frp-copilot-1.0.11
+- copilot-4.3
+- copilot-c99-4.3
+- copilot-core-4.3
+- copilot-language-4.3
+- copilot-libraries-4.3
+- copilot-theorem-4.3
+- copilot-interpreter-4.3
+- copilot-prettyprinter-4.3
 - language-c99-0.2.0
 - language-c99-simple-0.3.0
 - language-c99-util-0.2.0
diff --git a/Examples/EEPROMrange/stack.yaml b/Examples/EEPROMrange/stack.yaml
--- a/Examples/EEPROMrange/stack.yaml
+++ b/Examples/EEPROMrange/stack.yaml
@@ -3,15 +3,15 @@
 - '../..'
 resolver: lts-22.11
 extra-deps: 
-- sketch-frp-copilot-1.0.10
-- copilot-3.18.1
-- copilot-c99-3.18.1
-- copilot-core-3.18.1
-- copilot-language-3.18.1
-- copilot-libraries-3.18.1
-- copilot-theorem-3.18.1
-- copilot-interpreter-3.18.1
-- copilot-prettyprinter-3.18.1
+- sketch-frp-copilot-1.0.11
+- copilot-4.3
+- copilot-c99-4.3
+- copilot-core-4.3
+- copilot-language-4.3
+- copilot-libraries-4.3
+- copilot-theorem-4.3
+- copilot-interpreter-4.3
+- copilot-prettyprinter-4.3
 - language-c99-0.2.0
 - language-c99-simple-0.3.0
 - language-c99-util-0.2.0
diff --git a/Examples/Random/stack.yaml b/Examples/Random/stack.yaml
--- a/Examples/Random/stack.yaml
+++ b/Examples/Random/stack.yaml
@@ -3,15 +3,15 @@
 - '../..'
 resolver: lts-22.11
 extra-deps: 
-- sketch-frp-copilot-1.0.10
-- copilot-3.18.1
-- copilot-c99-3.18.1
-- copilot-core-3.18.1
-- copilot-language-3.18.1
-- copilot-libraries-3.18.1
-- copilot-theorem-3.18.1
-- copilot-interpreter-3.18.1
-- copilot-prettyprinter-3.18.1
+- sketch-frp-copilot-1.0.11
+- copilot-4.3
+- copilot-c99-4.3
+- copilot-core-4.3
+- copilot-language-4.3
+- copilot-libraries-4.3
+- copilot-theorem-4.3
+- copilot-interpreter-4.3
+- copilot-prettyprinter-4.3
 - language-c99-0.2.0
 - language-c99-simple-0.3.0
 - language-c99-util-0.2.0
diff --git a/Examples/SerialPort/stack.yaml b/Examples/SerialPort/stack.yaml
--- a/Examples/SerialPort/stack.yaml
+++ b/Examples/SerialPort/stack.yaml
@@ -3,15 +3,15 @@
 - '../..'
 resolver: lts-22.11
 extra-deps: 
-- sketch-frp-copilot-1.0.10
-- copilot-3.18.1
-- copilot-c99-3.18.1
-- copilot-core-3.18.1
-- copilot-language-3.18.1
-- copilot-libraries-3.18.1
-- copilot-theorem-3.18.1
-- copilot-interpreter-3.18.1
-- copilot-prettyprinter-3.18.1
+- sketch-frp-copilot-1.0.11
+- copilot-4.3
+- copilot-c99-4.3
+- copilot-core-4.3
+- copilot-language-4.3
+- copilot-libraries-4.3
+- copilot-theorem-4.3
+- copilot-interpreter-4.3
+- copilot-prettyprinter-4.3
 - language-c99-0.2.0
 - language-c99-simple-0.3.0
 - language-c99-util-0.2.0
diff --git a/Examples/WaterHeater/stack.yaml b/Examples/WaterHeater/stack.yaml
--- a/Examples/WaterHeater/stack.yaml
+++ b/Examples/WaterHeater/stack.yaml
@@ -3,15 +3,15 @@
 - '../..'
 resolver: lts-22.11
 extra-deps: 
-- sketch-frp-copilot-1.0.10
-- copilot-3.18.1
-- copilot-c99-3.18.1
-- copilot-core-3.18.1
-- copilot-language-3.18.1
-- copilot-libraries-3.18.1
-- copilot-theorem-3.18.1
-- copilot-interpreter-3.18.1
-- copilot-prettyprinter-3.18.1
+- sketch-frp-copilot-1.0.11
+- copilot-4.3
+- copilot-c99-4.3
+- copilot-core-4.3
+- copilot-language-4.3
+- copilot-libraries-4.3
+- copilot-theorem-4.3
+- copilot-interpreter-4.3
+- copilot-prettyprinter-4.3
 - language-c99-0.2.0
 - language-c99-simple-0.3.0
 - language-c99-util-0.2.0
diff --git a/arduino-copilot.cabal b/arduino-copilot.cabal
--- a/arduino-copilot.cabal
+++ b/arduino-copilot.cabal
@@ -1,5 +1,5 @@
 Name: arduino-copilot
-Version: 1.7.8
+Version: 1.7.9
 Cabal-Version: >= 1.10
 License: BSD3
 Maintainer: Joey Hess <id@joeyh.name>
@@ -114,10 +114,10 @@
     Copilot.Arduino.Main
   Build-Depends:
     base (>= 4.5 && < 5),
-    sketch-frp-copilot (== 1.0.10),
-    copilot (== 3.18.*),
-    copilot-c99 (== 3.18.*),
-    copilot-language (== 3.18.*),
+    sketch-frp-copilot (== 1.0.11),
+    copilot (== 4.3.*),
+    copilot-c99 (== 4.3.*),
+    copilot-language (== 4.3.*),
     filepath,
     directory,
     mtl,
diff --git a/src/Copilot/Arduino.hs b/src/Copilot/Arduino.hs
--- a/src/Copilot/Arduino.hs
+++ b/src/Copilot/Arduino.hs
@@ -77,7 +77,7 @@
 	module X,
 ) where
 
-import Language.Copilot as X hiding (Stream, ifThenElse)
+import Language.Copilot as X hiding (Stream, ifThenElse, (=:))
 import Language.Copilot (Stream)
 import Sketch.FRP.Copilot
 import Copilot.Arduino.Internals
diff --git a/stack.yaml b/stack.yaml
--- a/stack.yaml
+++ b/stack.yaml
@@ -2,15 +2,15 @@
 - '.'
 resolver: lts-22.11
 extra-deps:
-- sketch-frp-copilot-1.0.10
-- copilot-3.18.1
-- copilot-c99-3.18.1
-- copilot-core-3.18.1
-- copilot-language-3.18.1
-- copilot-libraries-3.18.1
-- copilot-theorem-3.18.1
-- copilot-interpreter-3.18.1
-- copilot-prettyprinter-3.18.1
+- sketch-frp-copilot-1.0.11
+- copilot-4.3
+- copilot-c99-4.3
+- copilot-core-4.3
+- copilot-language-4.3
+- copilot-libraries-4.3
+- copilot-theorem-4.3
+- copilot-interpreter-4.3
+- copilot-prettyprinter-4.3
 - language-c99-0.2.0
 - language-c99-simple-0.3.0
 - language-c99-util-0.2.0