diff --git a/Makefile b/Makefile
index 55bd735c..f85e9b91 100644
--- a/Makefile
+++ b/Makefile
@@ -9,9 +9,9 @@ MAKEFLAGS += --no-print-directory
 BIN := .tmp/bin
 CACHE := .tmp/cache
 LICENSE_HEADER_YEAR_RANGE := 2022-2023
-LICENSE_HEADER_VERSION := v1.28.1
+LICENSE_HEADER_VERSION := v1.30.0
 CONFORMANCE_VERSION := v1.0.0-rc3
-PROTOC_VERSION ?= 25.3
+PROTOC_VERSION ?= 26.0
 GRADLE_ARGS ?=
 PROTOC := $(BIN)/protoc
 CONNECT_CONFORMANCE := $(BIN)/connectconformance
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 2ccd0080..3851ed61 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -11,7 +11,7 @@ moshi = "1.15.1"
 okhttp = "4.12.0"
 okio = "3.9.0"
 # Ensure that PROTOC_VERSION in the Makefile is updated when changing this version.
-protobuf = "3.25.3"
+protobuf = "4.26.0"
 slf4j = "2.0.12"
 spotless = "6.25.0"