diff --git a/syswrap/mmap.go b/syswrap/mmap.go
index 4b680780a..238f6dd6f 100644
--- a/syswrap/mmap.go
+++ b/syswrap/mmap.go
@@ -36,8 +36,8 @@ var mu sync.RWMutex
 
 // SetMaxMapCount sets the maximum map count, and returns the previous maximum.
 func SetMaxMapCount(max uint64) uint64 {
-	prev := maxMapCount
 	mu.Lock()
+	prev := maxMapCount
 	maxMapCount = max
 	mu.Unlock()
 	return prev
diff --git a/syswrap/os.go b/syswrap/os.go
index 67f87fcd4..61715f5bb 100644
--- a/syswrap/os.go
+++ b/syswrap/os.go
@@ -28,8 +28,8 @@ var maxFileCount uint64 = 500000
 var fileMu sync.RWMutex
 
 func SetMaxFileCount(max uint64) uint64 {
-	prev := maxFileCount
 	fileMu.Lock()
+	prev := maxFileCount
 	maxFileCount = max
 	fileMu.Unlock()
 	return prev