diff --git a/build.gradle.kts b/build.gradle.kts
index cab5954..ba1746d 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -19,7 +19,7 @@ plugins {
     alias(libs.plugins.versions)
 }
 
-val baseVersion = "1.0.1"
+val baseVersion = "2.0.0"
 val isSnapshot = true
 
 val isCIServer = System.getenv("CTHING_CI") != null
@@ -39,7 +39,7 @@ java {
 // This project is a dependency of all C Thing Software projects. Therefore, to avoid circular
 // dependencies, it should not depend on any C Thing Software project.
 dependencies {
-    api(libs.jsr305)
+    api(libs.jspecify)
 
     testImplementation(libs.assertJ)
     testImplementation(libs.equalsVerifier)
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 7091a0e..3937983 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -13,7 +13,7 @@ versions = { id = "com.github.ben-manes.versions", version = "0.51.0" }
 [libraries]
 assertJ = "org.assertj:assertj-core:3.26.3"
 equalsVerifier = "nl.jqno.equalsverifier:equalsverifier:3.17.1"
-jsr305 = "com.google.code.findbugs:jsr305:3.0.2"
+jspecify = "org.jspecify:jspecify:1.0.0"
 junitApi = { module = "org.junit.jupiter:junit-jupiter-api", version.ref = "junit" }
 junitEngine = { module = "org.junit.jupiter:junit-jupiter-engine", version.ref = "junit" }
 junitLauncher = "org.junit.platform:junit-platform-launcher:1.11.2"
diff --git a/src/main/java/org/cthing/projectversion/ProjectVersion.java b/src/main/java/org/cthing/projectversion/ProjectVersion.java
index bdcb0b3..7895848 100644
--- a/src/main/java/org/cthing/projectversion/ProjectVersion.java
+++ b/src/main/java/org/cthing/projectversion/ProjectVersion.java
@@ -15,7 +15,7 @@
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-import javax.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 
 /**
diff --git a/src/main/java/org/cthing/projectversion/package-info.java b/src/main/java/org/cthing/projectversion/package-info.java
index b507057..8cfc95e 100644
--- a/src/main/java/org/cthing/projectversion/package-info.java
+++ b/src/main/java/org/cthing/projectversion/package-info.java
@@ -6,7 +6,7 @@
 /**
  * Provides a version object for C Thing Software projects.
  */
-@ParametersAreNonnullByDefault
+@NullMarked
 package org.cthing.projectversion;
 
-import javax.annotation.ParametersAreNonnullByDefault;
+import org.jspecify.annotations.NullMarked;