diff --git a/src/iperf.h b/src/iperf.h
index 7d14a3453..b541d2c8c 100644
--- a/src/iperf.h
+++ b/src/iperf.h
@@ -193,6 +193,7 @@ struct iperf_stream
     struct iperf_test* test;
 
     pthread_t thr;
+    int thread_created;
     int       done;
 
     /* configurable members */
diff --git a/src/iperf_client_api.c b/src/iperf_client_api.c
index 67b05cc69..8807541ff 100644
--- a/src/iperf_client_api.c
+++ b/src/iperf_client_api.c
@@ -715,6 +715,7 @@ iperf_run_client(struct iperf_test * test)
                         i_errno = IEPTHREADCREATE;
                         goto cleanup_and_fail;
                     }
+                    sp->thread_created = 1;
                     if (test->debug_level >= DEBUG_LEVEL_INFO) {
                         iperf_printf(test, "Thread FD %d created\n", sp->socket);
                     }
@@ -753,22 +754,25 @@ iperf_run_client(struct iperf_test * test)
                     if (sp->sender) {
                         int rc;
                         sp->done = 1;
-                        rc = pthread_cancel(sp->thr);
-                        if (rc != 0 && rc != ESRCH) {
-                            i_errno = IEPTHREADCANCEL;
-                            errno = rc;
-                            iperf_err(test, "sender cancel in pthread_cancel - %s", iperf_strerror(i_errno));
-                            goto cleanup_and_fail;
-                        }
-                        rc = pthread_join(sp->thr, NULL);
-                        if (rc != 0 && rc != ESRCH) {
-                            i_errno = IEPTHREADJOIN;
-                            errno = rc;
-                            iperf_err(test, "sender cancel in pthread_join - %s", iperf_strerror(i_errno));
-                            goto cleanup_and_fail;
-                        }
-                        if (test->debug_level >= DEBUG_LEVEL_INFO) {
-                            iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+                        if (sp->thread_created == 1) {
+                            rc = pthread_cancel(sp->thr);
+                            if (rc != 0 && rc != ESRCH) {
+                                i_errno = IEPTHREADCANCEL;
+                                errno = rc;
+                                iperf_err(test, "sender cancel in pthread_cancel - %s", iperf_strerror(i_errno));
+                                goto cleanup_and_fail;
+                            }
+                            rc = pthread_join(sp->thr, NULL);
+                            if (rc != 0 && rc != ESRCH) {
+                                i_errno = IEPTHREADJOIN;
+                                errno = rc;
+                                iperf_err(test, "sender cancel in pthread_join - %s", iperf_strerror(i_errno));
+                                goto cleanup_and_fail;
+                            }
+                            if (test->debug_level >= DEBUG_LEVEL_INFO) {
+                                iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+                            }
+                            sp->thread_created = 0;
                         }
                     }
                 }
@@ -791,22 +795,25 @@ iperf_run_client(struct iperf_test * test)
         if (!sp->sender) {
             int rc;
             sp->done = 1;
-            rc = pthread_cancel(sp->thr);
-            if (rc != 0 && rc != ESRCH) {
-                i_errno = IEPTHREADCANCEL;
-                errno = rc;
-                iperf_err(test, "receiver cancel in pthread_cancel - %s", iperf_strerror(i_errno));
-                goto cleanup_and_fail;
-            }
-            rc = pthread_join(sp->thr, NULL);
-            if (rc != 0 && rc != ESRCH) {
-                i_errno = IEPTHREADJOIN;
-                errno = rc;
-                iperf_err(test, "receiver cancel in pthread_join - %s", iperf_strerror(i_errno));
-                goto cleanup_and_fail;
-            }
-            if (test->debug_level >= DEBUG_LEVEL_INFO) {
-                iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+            if (sp->thread_created == 1) {
+                rc = pthread_cancel(sp->thr);
+                if (rc != 0 && rc != ESRCH) {
+                    i_errno = IEPTHREADCANCEL;
+                    errno = rc;
+                    iperf_err(test, "receiver cancel in pthread_cancel - %s", iperf_strerror(i_errno));
+                    goto cleanup_and_fail;
+                }
+                rc = pthread_join(sp->thr, NULL);
+                if (rc != 0 && rc != ESRCH) {
+                    i_errno = IEPTHREADJOIN;
+                    errno = rc;
+                    iperf_err(test, "receiver cancel in pthread_join - %s", iperf_strerror(i_errno));
+                    goto cleanup_and_fail;
+                }
+                if (test->debug_level >= DEBUG_LEVEL_INFO) {
+                    iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+                }
+                sp->thread_created = 0;
             }
         }
     }
@@ -835,20 +842,23 @@ iperf_run_client(struct iperf_test * test)
         }
         sp->done = 1;
         int rc;
-        rc = pthread_cancel(sp->thr);
-        if (rc != 0 && rc != ESRCH) {
-            i_errno = IEPTHREADCANCEL;
-            errno = rc;
-            iperf_err(test, "cleanup_and_fail in pthread_cancel - %s", iperf_strerror(i_errno));
-        }
-        rc = pthread_join(sp->thr, NULL); 
-        if (rc != 0 && rc != ESRCH) {
-            i_errno = IEPTHREADJOIN;
-            errno = rc;
-            iperf_err(test, "cleanup_and_fail in pthread_join - %s", iperf_strerror(i_errno));
-        }
-        if (test->debug_level >= DEBUG_LEVEL_INFO) {
-            iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+        if (sp->thread_created == 1) {
+            rc = pthread_cancel(sp->thr);
+            if (rc != 0 && rc != ESRCH) {
+                i_errno = IEPTHREADCANCEL;
+                errno = rc;
+                iperf_err(test, "cleanup_and_fail in pthread_cancel - %s", iperf_strerror(i_errno));
+            }
+            rc = pthread_join(sp->thr, NULL); 
+            if (rc != 0 && rc != ESRCH) {
+                i_errno = IEPTHREADJOIN;
+                errno = rc;
+                iperf_err(test, "cleanup_and_fail in pthread_join - %s", iperf_strerror(i_errno));
+            }
+            if (test->debug_level >= DEBUG_LEVEL_INFO) {
+                iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+            }
+            sp->thread_created = 0;
         }
     }
     if (test->debug_level >= DEBUG_LEVEL_INFO) {
diff --git a/src/iperf_server_api.c b/src/iperf_server_api.c
index 9727cdddb..aa601c3ec 100644
--- a/src/iperf_server_api.c
+++ b/src/iperf_server_api.c
@@ -448,20 +448,23 @@ cleanup_server(struct iperf_test *test)
     SLIST_FOREACH(sp, &test->streams, streams) {
         int rc;
         sp->done = 1;
-        rc = pthread_cancel(sp->thr);
-        if (rc != 0 && rc != ESRCH) {
-            i_errno = IEPTHREADCANCEL;
-            errno = rc;
-            iperf_err(test, "cleanup_server in pthread_cancel - %s", iperf_strerror(i_errno));
-        }
-        rc = pthread_join(sp->thr, NULL);
-        if (rc != 0 && rc != ESRCH) {
-            i_errno = IEPTHREADJOIN;
-            errno = rc;
-            iperf_err(test, "cleanup_server in pthread_join - %s", iperf_strerror(i_errno));
-        }
-        if (test->debug_level >= DEBUG_LEVEL_INFO) {
-            iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+        if (sp->thread_created == 1) {
+            rc = pthread_cancel(sp->thr);
+            if (rc != 0 && rc != ESRCH) {
+                i_errno = IEPTHREADCANCEL;
+                errno = rc;
+                iperf_err(test, "cleanup_server in pthread_cancel - %s", iperf_strerror(i_errno));
+            }
+            rc = pthread_join(sp->thr, NULL);
+            if (rc != 0 && rc != ESRCH) {
+                i_errno = IEPTHREADJOIN;
+                errno = rc;
+                iperf_err(test, "cleanup_server in pthread_join - %s", iperf_strerror(i_errno));
+            }
+            if (test->debug_level >= DEBUG_LEVEL_INFO) {
+                iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+            }
+            sp->thread_created = 0;
         }
     }
     i_errno = i_errno_save;
@@ -909,6 +912,7 @@ iperf_run_server(struct iperf_test *test)
                             cleanup_server(test);
                             return -1;
                         }
+                        sp->thread_created = 1;
                         if (test->debug_level >= DEBUG_LEVEL_INFO) {
                             iperf_printf(test, "Thread FD %d created\n", sp->socket);
                         }