diff --git a/executor/common.h b/executor/common.h
index e1cc3385eb3..b087978a5b2 100644
--- a/executor/common.h
+++ b/executor/common.h
@@ -13,8 +13,6 @@
 #include <unistd.h>
 #if defined(SYZ_EXECUTOR) || defined(SYZ_THREADED) || defined(SYZ_COLLIDE)
 #include <pthread.h>
-#endif
-#if defined(SYZ_EXECUTOR) || defined(SYZ_COLLIDE)
 #include <stdlib.h>
 #endif
 #if defined(SYZ_EXECUTOR) || defined(SYZ_HANDLE_SEGV)
diff --git a/pkg/csource/common.go b/pkg/csource/common.go
index 90b1943fc23..a2fcd6897de 100644
--- a/pkg/csource/common.go
+++ b/pkg/csource/common.go
@@ -14,8 +14,6 @@ var commonHeader = `
 #include <unistd.h>
 #if defined(SYZ_EXECUTOR) || defined(SYZ_THREADED) || defined(SYZ_COLLIDE)
 #include <pthread.h>
-#endif
-#if defined(SYZ_EXECUTOR) || defined(SYZ_COLLIDE)
 #include <stdlib.h>
 #endif
 #if defined(SYZ_EXECUTOR) || defined(SYZ_HANDLE_SEGV)
diff --git a/pkg/csource/csource.go b/pkg/csource/csource.go
index e52be3e8856..32415e9829b 100644
--- a/pkg/csource/csource.go
+++ b/pkg/csource/csource.go
@@ -219,7 +219,7 @@ func generateTestFunc(w io.Writer, opts Options, calls []string, name string) {
 		}
 		fmt.Fprintf(w, "\tfor (i = 0; i < %v; i++) {\n", len(calls))
 		fmt.Fprintf(w, "\t\tpthread_create(&th[i], 0, thr, (void*)i);\n")
-		fmt.Fprintf(w, "\t\tusleep(10000);\n")
+		fmt.Fprintf(w, "\t\tusleep(rand()%%10000);\n")
 		fmt.Fprintf(w, "\t}\n")
 		if opts.Collide {
 			fmt.Fprintf(w, "\tfor (i = 0; i < %v; i++) {\n", len(calls))
@@ -228,7 +228,7 @@ func generateTestFunc(w io.Writer, opts Options, calls []string, name string) {
 			fmt.Fprintf(w, "\t\t\tusleep(rand()%%10000);\n")
 			fmt.Fprintf(w, "\t}\n")
 		}
-		fmt.Fprintf(w, "\tusleep(100000);\n")
+		fmt.Fprintf(w, "\tusleep(rand()%%100000);\n")
 		fmt.Fprintf(w, "}\n\n")
 	}
 }