diff --git a/buildSrc/src/main/kotlin/publish.gradle.kts b/buildSrc/src/main/kotlin/publish.gradle.kts
index 697d4b4..b9ac925 100644
--- a/buildSrc/src/main/kotlin/publish.gradle.kts
+++ b/buildSrc/src/main/kotlin/publish.gradle.kts
@@ -6,7 +6,12 @@ plugins {
 
 mavenPublishing {
     publishToMavenCentral()
-    signAllPublications()
+    // Only sign when a key is actually configured (CI's release job sets this via
+    // ORG_GRADLE_PROJECT_signingInMemoryKey). Signing unconditionally breaks `publishToMavenLocal`
+    // for local development/testing, since no GPG key is available outside the release job.
+    if (project.hasProperty("signingInMemoryKey")) {
+        signAllPublications()
+    }
 
     pom {
         name.set(project.name)