diff --git a/org.lflang.tests/src/org/lflang/tests/Configurators.java b/org.lflang.tests/src/org/lflang/tests/Configurators.java
index 24ee6f38f3..85a8465c29 100644
--- a/org.lflang.tests/src/org/lflang/tests/Configurators.java
+++ b/org.lflang.tests/src/org/lflang/tests/Configurators.java
@@ -25,6 +25,7 @@
 package org.lflang.tests;
 
 import org.lflang.TargetProperty;
+import org.lflang.TargetProperty.LogLevel;
 import org.lflang.TargetProperty.Platform;
 import org.lflang.tests.TestRegistry.TestCategory;
 
@@ -63,13 +64,28 @@ public static boolean disableThreading(LFTest test) {
     return true;
   }
 
-  public static boolean makeZephyrCompatible(LFTest test) {
+  public static boolean makeZephyrCompatibleUnthreaded(LFTest test) {
     test.getContext().getArgs().setProperty("tracing", "false");
     test.getContext().getTargetConfig().threading = false;
     test.getContext().getTargetConfig().setByUser.add(TargetProperty.THREADING);
     test.getContext().getTargetConfig().platformOptions.platform = Platform.ZEPHYR;
     test.getContext().getTargetConfig().platformOptions.flash = false;
-    test.getContext().getTargetConfig().platformOptions.board = "qemu_cortex_a53";
+    test.getContext().getTargetConfig().platformOptions.board = "qemu_riscv32";
+    // FIXME: Zephyr qemu emulations fails with debug log-levels.
+    test.getContext().getTargetConfig().logLevel = LogLevel.WARN;
+    test.getContext().getArgs().setProperty("logging", "warning");
+    return true;
+  }
+
+  public static boolean makeZephyrCompatible(LFTest test) {
+    test.getContext().getArgs().setProperty("tracing", "false");
+    test.getContext().getTargetConfig().platformOptions.platform = Platform.ZEPHYR;
+    test.getContext().getTargetConfig().platformOptions.flash = false;
+    test.getContext().getTargetConfig().platformOptions.board = "qemu_riscv32";
+    // FIXME: Zephyr qemu emulations fails with debug log-levels.
+    test.getContext().getTargetConfig().logLevel = LogLevel.WARN;
+    test.getContext().getArgs().setProperty("logging", "warning");
+
     return true;
   }
   /**
diff --git a/org.lflang.tests/src/org/lflang/tests/runtime/CZephyrTest.java b/org.lflang.tests/src/org/lflang/tests/runtime/CZephyrTest.java
index c151c1bb76..b29c2755d1 100644
--- a/org.lflang.tests/src/org/lflang/tests/runtime/CZephyrTest.java
+++ b/org.lflang.tests/src/org/lflang/tests/runtime/CZephyrTest.java
@@ -62,6 +62,19 @@ public void buildGenericTests() {
         List.of(Target.C),
         Message.DESC_GENERIC,
         TestCategory.GENERIC::equals,
+        Configurators::makeZephyrCompatibleUnthreaded,
+        TestLevel.BUILD,
+        false);
+  }
+
+  @Test
+  public void buildConcurrentTests() {
+    Assumptions.assumeTrue(isLinux(), "Zephyr tests only run on Linux");
+
+    super.runTestsFor(
+        List.of(Target.C),
+        Message.DESC_CONCURRENT,
+        TestCategory.CONCURRENT::equals,
         Configurators::makeZephyrCompatible,
         TestLevel.BUILD,
         false);
diff --git a/org.lflang/src/org/lflang/TargetConfig.java b/org.lflang/src/org/lflang/TargetConfig.java
index c4794b4b1a..af805491da 100644
--- a/org.lflang/src/org/lflang/TargetConfig.java
+++ b/org.lflang/src/org/lflang/TargetConfig.java
@@ -397,6 +397,12 @@ public static class PlatformOptions {
      * you use to flash the boards.
      */
     public boolean flash = false;
+
+    /**
+     * The int value is used to determine the number of needed threads for the user application in
+     * Zephyr.
+     */
+    public int userThreads = 0;
   }
 
   /** Settings related to tracing options. */
diff --git a/org.lflang/src/org/lflang/TargetProperty.java b/org.lflang/src/org/lflang/TargetProperty.java
index b3abf815a3..796041b5f8 100644
--- a/org.lflang/src/org/lflang/TargetProperty.java
+++ b/org.lflang/src/org/lflang/TargetProperty.java
@@ -445,6 +445,9 @@ public enum TargetProperty {
             case PORT:
               pair.setValue(ASTUtils.toElement(config.platformOptions.port));
               break;
+            case USER_THREADS:
+              pair.setValue(ASTUtils.toElement(config.platformOptions.userThreads));
+              break;
           }
           kvp.getPairs().add(pair);
         }
@@ -489,6 +492,9 @@ public enum TargetProperty {
               case PORT:
                 config.platformOptions.port = ASTUtils.elementToSingleString(entry.getValue());
                 break;
+              case USER_THREADS:
+                config.platformOptions.userThreads = ASTUtils.toInteger(entry.getValue());
+                break;
               default:
                 break;
             }
@@ -1629,7 +1635,8 @@ public enum PlatformOption implements DictionaryElement {
     BAUDRATE("baud-rate", PrimitiveType.NON_NEGATIVE_INTEGER),
     BOARD("board", PrimitiveType.STRING),
     FLASH("flash", PrimitiveType.BOOLEAN),
-    PORT("port", PrimitiveType.STRING);
+    PORT("port", PrimitiveType.STRING),
+    USER_THREADS("user-threads", PrimitiveType.NON_NEGATIVE_INTEGER);
 
     public final PrimitiveType type;
 
diff --git a/org.lflang/src/org/lflang/generator/c/CGenerator.java b/org.lflang/src/org/lflang/generator/c/CGenerator.java
index a8aeb271b5..f3accf165a 100644
--- a/org.lflang/src/org/lflang/generator/c/CGenerator.java
+++ b/org.lflang/src/org/lflang/generator/c/CGenerator.java
@@ -56,6 +56,7 @@
 import org.lflang.TargetConfig;
 import org.lflang.TargetProperty;
 import org.lflang.TargetProperty.Platform;
+import org.lflang.TargetProperty.PlatformOption;
 import org.lflang.ast.ASTUtils;
 import org.lflang.ast.DelayedConnectionTransformation;
 import org.lflang.federated.extensions.CExtensionUtils;
@@ -713,9 +714,9 @@ private void generateCodeFor(String lfModuleName) throws IOException {
       // from the federation and close any open sockets.
       code.pr(
           """
-                #ifndef FEDERATED
-                void terminate_execution() {}
-                #endif""");
+                 #ifndef FEDERATED
+                 void terminate_execution() {}
+                 #endif""");
 
       // Generate functions for modes
       code.pr(CModesGenerator.generateLfInitializeModes(hasModalReactors));
@@ -1142,13 +1143,13 @@ protected void generateAuxiliaryStructs(
     federatedExtension.pr(
         String.format(
             """
-            #ifdef FEDERATED
-            #ifdef FEDERATED_DECENTRALIZED
-            %s intended_tag;
-            #endif
-            %s physical_time_of_arrival;
-            #endif
-            """,
+             #ifdef FEDERATED
+             #ifdef FEDERATED_DECENTRALIZED
+             %s intended_tag;
+             #endif
+             %s physical_time_of_arrival;
+             #endif
+             """,
             types.getTargetTagType(), types.getTargetTimeType()));
     for (Port p : allPorts(tpr.reactor())) {
       builder.pr(
@@ -2009,6 +2010,19 @@ protected void setUpGeneralParameters() {
               + " code only.");
       targetConfig.noCompile = true;
     }
+
+    if (targetConfig.platformOptions.platform == Platform.ZEPHYR
+        && targetConfig.threading
+        && targetConfig.platformOptions.userThreads >= 0) {
+      targetConfig.compileDefinitions.put(
+          PlatformOption.USER_THREADS.name(),
+          String.valueOf(targetConfig.platformOptions.userThreads));
+    } else if (targetConfig.platformOptions.userThreads > 0) {
+      errorReporter.reportWarning(
+          "Specifying user threads is only for threaded Lingua Franca on the Zephyr platform. This"
+              + " option will be ignored.");
+    }
+
     if (targetConfig.threading) { // FIXME: This logic is duplicated in CMake
       pickScheduler();
       // FIXME: this and pickScheduler should be combined.
diff --git a/test/C/lib/libapp.a b/test/C/lib/libapp.a
new file mode 100644
index 0000000000..d710e87c0e
Binary files /dev/null and b/test/C/lib/libapp.a differ
diff --git a/test/C/src/zephyr/Timer.lf b/test/C/src/zephyr/Timer.lf
index d3cb3f96de..a3dd0e68cc 100644
--- a/test/C/src/zephyr/Timer.lf
+++ b/test/C/src/zephyr/Timer.lf
@@ -3,7 +3,6 @@ target C {
         name: Zephyr,
         board: qemu_cortex_m3
     },
-    threading: false,
     timeout: 10 sec
 }
 
diff --git a/test/C/src/zephyr/UserThreads.lf b/test/C/src/zephyr/UserThreads.lf
new file mode 100644
index 0000000000..115d8114a7
--- /dev/null
+++ b/test/C/src/zephyr/UserThreads.lf
@@ -0,0 +1,39 @@
+// Test user threads platform option for Zephyr. The application should be able
+// to create exactly three threads.
+target C {
+    platform: {
+        name: Zephyr,
+        user-threads: 3
+    },
+    threading: true,
+    workers: 2
+}
+
+main reactor {
+    preamble {=
+        #include "platform.h"
+        void func(void* arg) {
+            lf_print("Hello from user thread");
+        }
+
+        lf_thread_t thread_ids[4];
+    =}
+
+    reaction(startup) {=
+        int res;
+
+        for (int i = 0; i < 3; i++) {
+            res = lf_thread_create(&thread_ids[i], &func, NULL);
+            if (res != 0) {
+                lf_print_error_and_exit("Could not create thread");
+            }
+        }
+
+        res = lf_thread_create(&thread_ids[3], &func, NULL);
+        if (res == 0) {
+            lf_print_error_and_exit("Could create more threads than specified.");
+        } else {
+            printf("SUCCESS: Created exactly three user threads.\n");
+        }
+    =}
+}
diff --git a/util/RunZephyrTests.sh b/util/RunZephyrTests.sh
index 742a23ef18..ffb15198a9 100755
--- a/util/RunZephyrTests.sh
+++ b/util/RunZephyrTests.sh
@@ -9,7 +9,7 @@ num_failures=0
 failed_tests=""
 
 # Skip
-skip=("FileReader" "FilePkgReader")
+skip=("FileReader" "FilePkgReader" "Tracing" "ThreadedThreaded")
 
 find_kconfig_folders() {
     if [ -f "$folder/CMakeLists.txt" ]; then
@@ -116,8 +116,7 @@ else
 fi
 echo "Number of passes: $num_successes"
 echo "Number of fails: $num_failures"
-echo "Skipped tests: $skip"
-
+echo "Skipped tests: ${skip[@]}"
 
 if [ "$overall_success" = false ]; then
     echo "Failed tests: $failed_tests"