diff --git a/README.md b/README.md
index 49e6713..e1e4c69 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ Generate the project and unzip the downloaded result.
 
 Open it in your IDE in the usual way. E.g. if you’re using IntelliJ IDEA: `idea pom.xml`; or for VSCode `code .`.
 
-Define a `.proto` service definition file `src/main/protobuf/hello.proto` with the following contents:
+Define a `.proto` service definition file `src/main/proto/hello.proto` with the following contents:
 
 ```proto
 syntax = "proto3";
diff --git a/samples/grpc-client/build.gradle b/samples/grpc-client/build.gradle
index 65c0135..55ff1c2 100644
--- a/samples/grpc-client/build.gradle
+++ b/samples/grpc-client/build.gradle
@@ -39,14 +39,6 @@ tasks.named('test') {
     useJUnitPlatform()
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-client/pom.xml b/samples/grpc-client/pom.xml
index bc7786e..75babb0 100644
--- a/samples/grpc-client/pom.xml
+++ b/samples/grpc-client/pom.xml
@@ -105,8 +105,11 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<protocVersion>${protobuf-java.version}</protocVersion>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
diff --git a/samples/grpc-client/src/main/protobuf/hello.proto b/samples/grpc-client/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-client/src/main/protobuf/hello.proto
rename to samples/grpc-client/src/main/proto/hello.proto
diff --git a/samples/grpc-oauth2/build.gradle b/samples/grpc-oauth2/build.gradle
index 01ae2cd..312ae11 100644
--- a/samples/grpc-oauth2/build.gradle
+++ b/samples/grpc-oauth2/build.gradle
@@ -49,14 +49,6 @@ test {
     outputs.upToDateWhen { false }
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-oauth2/pom.xml b/samples/grpc-oauth2/pom.xml
index 8872c22..bb33953 100644
--- a/samples/grpc-oauth2/pom.xml
+++ b/samples/grpc-oauth2/pom.xml
@@ -116,8 +116,11 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<protocVersion>${protobuf-java.version}</protocVersion>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
diff --git a/samples/grpc-oauth2/src/main/protobuf/hello.proto b/samples/grpc-oauth2/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-oauth2/src/main/protobuf/hello.proto
rename to samples/grpc-oauth2/src/main/proto/hello.proto
diff --git a/samples/grpc-reactive/build.gradle b/samples/grpc-reactive/build.gradle
index b705ce1..7f646b4 100644
--- a/samples/grpc-reactive/build.gradle
+++ b/samples/grpc-reactive/build.gradle
@@ -47,14 +47,6 @@ test {
     outputs.upToDateWhen { false }
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-reactive/pom.xml b/samples/grpc-reactive/pom.xml
index 1d2a4a8..fdf1ccf 100644
--- a/samples/grpc-reactive/pom.xml
+++ b/samples/grpc-reactive/pom.xml
@@ -131,8 +131,11 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<protocVersion>${protobuf-java.version}</protocVersion>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
diff --git a/samples/grpc-reactive/src/main/protobuf/hello.proto b/samples/grpc-reactive/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-reactive/src/main/protobuf/hello.proto
rename to samples/grpc-reactive/src/main/proto/hello.proto
diff --git a/samples/grpc-secure/build.gradle b/samples/grpc-secure/build.gradle
index 89b60d6..58d79b7 100644
--- a/samples/grpc-secure/build.gradle
+++ b/samples/grpc-secure/build.gradle
@@ -42,14 +42,6 @@ test {
     outputs.upToDateWhen { false }
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-secure/pom.xml b/samples/grpc-secure/pom.xml
index 94b7261..b775b1c 100644
--- a/samples/grpc-secure/pom.xml
+++ b/samples/grpc-secure/pom.xml
@@ -109,8 +109,11 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<protocVersion>${protobuf-java.version}</protocVersion>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
diff --git a/samples/grpc-secure/src/main/protobuf/hello.proto b/samples/grpc-secure/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-secure/src/main/protobuf/hello.proto
rename to samples/grpc-secure/src/main/proto/hello.proto
diff --git a/samples/grpc-server-kotlin/build.gradle b/samples/grpc-server-kotlin/build.gradle
index 908e059..8835234 100644
--- a/samples/grpc-server-kotlin/build.gradle
+++ b/samples/grpc-server-kotlin/build.gradle
@@ -53,14 +53,6 @@ test {
     outputs.upToDateWhen { false }
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-server-kotlin/pom.xml b/samples/grpc-server-kotlin/pom.xml
index 633063a..266ed75 100644
--- a/samples/grpc-server-kotlin/pom.xml
+++ b/samples/grpc-server-kotlin/pom.xml
@@ -143,8 +143,11 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<protocVersion>${protobuf-java.version}</protocVersion>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
diff --git a/samples/grpc-server-kotlin/src/main/protobuf/hello.proto b/samples/grpc-server-kotlin/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-server-kotlin/src/main/protobuf/hello.proto
rename to samples/grpc-server-kotlin/src/main/proto/hello.proto
diff --git a/samples/grpc-server-netty-shaded/build.gradle b/samples/grpc-server-netty-shaded/build.gradle
index 727876f..af776ef 100644
--- a/samples/grpc-server-netty-shaded/build.gradle
+++ b/samples/grpc-server-netty-shaded/build.gradle
@@ -47,14 +47,6 @@ test {
     outputs.upToDateWhen { false }
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-server-netty-shaded/pom.xml b/samples/grpc-server-netty-shaded/pom.xml
index 1985bca..e495963 100644
--- a/samples/grpc-server-netty-shaded/pom.xml
+++ b/samples/grpc-server-netty-shaded/pom.xml
@@ -106,8 +106,11 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<protocVersion>${protobuf-java.version}</protocVersion>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
diff --git a/samples/grpc-server-netty-shaded/src/main/protobuf/hello.proto b/samples/grpc-server-netty-shaded/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-server-netty-shaded/src/main/protobuf/hello.proto
rename to samples/grpc-server-netty-shaded/src/main/proto/hello.proto
diff --git a/samples/grpc-server/build.gradle b/samples/grpc-server/build.gradle
index ea34b41..c3e8d6f 100644
--- a/samples/grpc-server/build.gradle
+++ b/samples/grpc-server/build.gradle
@@ -43,14 +43,6 @@ test {
     outputs.upToDateWhen { false }
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-server/pom.xml b/samples/grpc-server/pom.xml
index 30e6b22..3bbbcd6 100644
--- a/samples/grpc-server/pom.xml
+++ b/samples/grpc-server/pom.xml
@@ -112,9 +112,12 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
 					<protocVersion>${protobuf-java.version}</protocVersion>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
 							<groupId>io.grpc</groupId>
diff --git a/samples/grpc-server/src/main/protobuf/hello.proto b/samples/grpc-server/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-server/src/main/protobuf/hello.proto
rename to samples/grpc-server/src/main/proto/hello.proto
diff --git a/samples/grpc-tomcat-secure/build.gradle b/samples/grpc-tomcat-secure/build.gradle
index 155a63c..da5db8b 100644
--- a/samples/grpc-tomcat-secure/build.gradle
+++ b/samples/grpc-tomcat-secure/build.gradle
@@ -43,14 +43,6 @@ test {
     outputs.upToDateWhen { false }
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-tomcat-secure/pom.xml b/samples/grpc-tomcat-secure/pom.xml
index cf56dc2..4189441 100644
--- a/samples/grpc-tomcat-secure/pom.xml
+++ b/samples/grpc-tomcat-secure/pom.xml
@@ -104,8 +104,11 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<protocVersion>${protobuf-java.version}</protocVersion>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
diff --git a/samples/grpc-tomcat-secure/src/main/protobuf/hello.proto b/samples/grpc-tomcat-secure/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-tomcat-secure/src/main/protobuf/hello.proto
rename to samples/grpc-tomcat-secure/src/main/proto/hello.proto
diff --git a/samples/grpc-tomcat/build.gradle b/samples/grpc-tomcat/build.gradle
index 9c563b0..211968c 100644
--- a/samples/grpc-tomcat/build.gradle
+++ b/samples/grpc-tomcat/build.gradle
@@ -43,14 +43,6 @@ test {
     outputs.upToDateWhen { false }
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-tomcat/pom.xml b/samples/grpc-tomcat/pom.xml
index be708de..5fc0576 100644
--- a/samples/grpc-tomcat/pom.xml
+++ b/samples/grpc-tomcat/pom.xml
@@ -109,8 +109,11 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<protocVersion>${protobuf-java.version}</protocVersion>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
diff --git a/samples/grpc-tomcat/src/main/protobuf/hello.proto b/samples/grpc-tomcat/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-tomcat/src/main/protobuf/hello.proto
rename to samples/grpc-tomcat/src/main/proto/hello.proto
diff --git a/samples/grpc-webflux/build.gradle b/samples/grpc-webflux/build.gradle
index 3e8830f..f6c2d59 100644
--- a/samples/grpc-webflux/build.gradle
+++ b/samples/grpc-webflux/build.gradle
@@ -42,14 +42,6 @@ test {
     outputs.upToDateWhen { false }
 }
 
-sourceSets {
-  main {
-    proto {
-      srcDir 'src/main/protobuf'
-    }
-  }
-}
-
 protobuf {
     protoc {
         artifact = "com.google.protobuf:protoc:${dependencyManagement.importedProperties['protobuf-java.version']}"
diff --git a/samples/grpc-webflux/pom.xml b/samples/grpc-webflux/pom.xml
index d253f7f..d76b76a 100644
--- a/samples/grpc-webflux/pom.xml
+++ b/samples/grpc-webflux/pom.xml
@@ -104,8 +104,11 @@
 			<plugin>
 				<groupId>io.github.ascopes</groupId>
 				<artifactId>protobuf-maven-plugin</artifactId>
-				<version>3.2.3</version>
+				<version>3.3.1</version>
 				<configuration>
+					<sourceDirectories>
+						<sourceDirectory>src/main/proto</sourceDirectory>
+					</sourceDirectories>
 					<protocVersion>${protobuf-java.version}</protocVersion>
 					<binaryMavenPlugins>
 						<binaryMavenPlugin>
diff --git a/samples/grpc-webflux/src/main/protobuf/hello.proto b/samples/grpc-webflux/src/main/proto/hello.proto
similarity index 100%
rename from samples/grpc-webflux/src/main/protobuf/hello.proto
rename to samples/grpc-webflux/src/main/proto/hello.proto
diff --git a/spring-grpc-docs/src/main/antora/modules/ROOT/pages/getting-started.adoc b/spring-grpc-docs/src/main/antora/modules/ROOT/pages/getting-started.adoc
index 0b20afe..fe4fc70 100644
--- a/spring-grpc-docs/src/main/antora/modules/ROOT/pages/getting-started.adoc
+++ b/spring-grpc-docs/src/main/antora/modules/ROOT/pages/getting-started.adoc
@@ -11,7 +11,7 @@ Generate the project and unzip the downloaded result.
 
 Open it in your IDE in the usual way. E.g. if you're using IntelliJ IDEA: `idea pom.xml`; or for VSCode `code .`.
 
-Define a `.proto` service definition file `src/main/protobuf/hello.proto` with the following contents:
+Define a `.proto` service definition file `src/main/proto/hello.proto` with the following contents:
 
 [source,proto]
 ----