diff --git a/build.sbt b/build.sbt
index 437677c02f..03857c2a7d 100644
--- a/build.sbt
+++ b/build.sbt
@@ -363,7 +363,7 @@ Global / tlCommandAliases ++= Map(
 
 lazy val nativeTestSettings = Seq(
   nativeConfig ~= { c =>
-    c.withSourceLevelDebuggingConfig(_.enableAll.generateFunctionSourcePositions(false))
+    c.withSourceLevelDebuggingConfig(_.enableAll)
       .withOptimize(
         true
       ) // `false` doesn't work due to https://github.com/scala-native/scala-native/issues/4366
diff --git a/core/native/src/main/resources/scala-native/signal_helper.c b/core/native/src/main/resources/scala-native/signal_helper.c
index 52c13c9dde..50b4786332 100644
--- a/core/native/src/main/resources/scala-native/signal_helper.c
+++ b/core/native/src/main/resources/scala-native/signal_helper.c
@@ -1,4 +1,10 @@
 #ifdef CATS_EFFECT_SIGNAL_HELPER
+
+// we'll need POSIX for `sigaction`:
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 1
+#endif
+
 #include <stddef.h>
 #include <signal.h>
 
@@ -19,4 +25,5 @@ int cats_effect_install_handler(int signum, Handler handler) {
     }
     return sigaction(signum, &action, NULL);
 }
+
 #endif
diff --git a/project/plugins.sbt b/project/plugins.sbt
index aa8c3e8cf7..8060409b75 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -3,7 +3,7 @@ libraryDependencies += "org.scala-js" %% "scalajs-env-selenium" % "1.1.1"
 addSbtPlugin("org.typelevel" % "sbt-typelevel" % "0.8.0")
 
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.18.2")
-addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.5.8")
+addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.5.9")
 addSbtPlugin("pl.project13.scala" % "sbt-jmh" % "0.4.7")
 addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.7.2")
 addSbtPlugin("com.lightbend.sbt" % "sbt-java-formatter" % "0.8.0")
diff --git a/tests/shared/src/test/scala/cats/effect/IOFiberSuite.scala b/tests/shared/src/test/scala/cats/effect/IOFiberSuite.scala
index 8a259f562b..6d7e5d4679 100644
--- a/tests/shared/src/test/scala/cats/effect/IOFiberSuite.scala
+++ b/tests/shared/src/test/scala/cats/effect/IOFiberSuite.scala
@@ -33,7 +33,7 @@ class IOFiberSuite extends BaseSuite with DetectPlatform {
         s <- IO(f.toString)
         // _ <- IO.println(s)
         _ <- f.cancel
-        _ <- IO(assert(s.matches(pattern)))
+        _ <- IO(assert(s.matches(pattern), s))
       } yield ()
     }
 
@@ -48,7 +48,7 @@ class IOFiberSuite extends BaseSuite with DetectPlatform {
         _ <- IO.sleep(100.milli)
         s <- IO(f.toString)
         _ <- f.cancel
-        _ <- IO(assert(s.matches(pattern)))
+        _ <- IO(assert(s.matches(pattern), s))
       } yield ()
     }
   } else {