diff --git a/collects/macro-debugger/analysis/private/moduledb.rkt b/collects/macro-debugger/analysis/private/moduledb.rkt
index 723a962c5e..7a2ec03691 100644
--- a/collects/macro-debugger/analysis/private/moduledb.rkt
+++ b/collects/macro-debugger/analysis/private/moduledb.rkt
@@ -32,10 +32,11 @@
     (cond [(symbol? name) 'no-bypass]
           [(hash-ref module-db name #f)
            => values]
-          [else
+          [(path? name)
            (let ([str (path->relative-string/library name)])
              (for/or ([rx (in-list no-bypass-rxs)])
-               (and (regexp-match? rx str) 'no-bypass)))])))
+               (and (regexp-match? rx str) 'no-bypass)))]
+          [else #f])))
 
 ;; module-db : ModuleDB
 (define module-db
diff --git a/collects/macro-debugger/analysis/private/util.rkt b/collects/macro-debugger/analysis/private/util.rkt
index fe0b8ec11c..a1118708ad 100644
--- a/collects/macro-debugger/analysis/private/util.rkt
+++ b/collects/macro-debugger/analysis/private/util.rkt
@@ -48,12 +48,17 @@
          mpi-list->module-path)
 
 ;; get-module-derivation : module-path -> (values compiled Deriv)
-(define (get-module-code/trace path)
-  (get-module-code (resolve-module-path path #f)
-                   #:choose (lambda _ 'src)
-                   #:compile (lambda (stx)
-                               (let-values ([(stx deriv) (trace/result stx expand)])
-                                 (values (compile stx) deriv)))))
+(define (get-module-code/trace modpath)
+  (let-values ([(path subs)
+                (match (resolve-module-path modpath #f)
+                  [`(submod ,path . ,subs) (values path subs)]
+                  [path (values path null)])])
+    (get-module-code path
+                     #:submodule-path subs
+                     #:choose (lambda _ 'src)
+                     #:compile (lambda (stx)
+                                 (let-values ([(stx deriv) (trace/result stx expand)])
+                                   (values (compile stx) deriv))))))
 
 ;; here-mpi? : any -> boolean
 (define (here-mpi? x)
@@ -96,19 +101,22 @@
                             (collapse-module-path mod (lambda () (loop base)))]
                            [else (build-path 'same)]))]
                   [else (build-path 'same)]))])
-    (match collapsed
-      [(list 'lib str)
-       (cond [(regexp-match? #rx"\\.rkt$" str)
-              (let* ([no-suffix (path->string (path-replace-suffix str ""))]
-                     [no-main
-                      (cond [(regexp-match #rx"^([^/]+)/main$" no-suffix)
-                             => cadr]
-                            [else no-suffix])])
-                (string->symbol no-main))]
-             [else collapsed])]
-      [(? path?)
-       (path->string (simplify-path collapsed #f))] ;; to get rid of "./" at beginning
-      [_ collapsed])))
+    (let simplify ([collapsed collapsed])
+      (match collapsed
+        [(list* 'submod base subs)
+         (list* 'submod (simplify base) subs)]
+        [(list 'lib str)
+         (cond [(regexp-match? #rx"\\.rkt$" str)
+                (let* ([no-suffix (path->string (path-replace-suffix str ""))]
+                       [no-main
+                        (cond [(regexp-match #rx"^([^/]+)/main$" no-suffix)
+                               => cadr]
+                              [else no-suffix])])
+                  (string->symbol no-main))]
+               [else collapsed])]
+        [(? path?)
+         (path->string (simplify-path collapsed #f))] ;; to get rid of "./" at beginning
+        [_ collapsed]))))
 
 ;; --------
 
diff --git a/collects/tests/macro-debugger/check-requires/src-a.rkt b/collects/tests/macro-debugger/check-requires/src-a.rkt
new file mode 100644
index 0000000000..348b93accf
--- /dev/null
+++ b/collects/tests/macro-debugger/check-requires/src-a.rkt
@@ -0,0 +1,3 @@
+#lang racket/base
+(define a 1)
+(provide a)
diff --git a/collects/tests/macro-debugger/check-requires/src-b.rkt b/collects/tests/macro-debugger/check-requires/src-b.rkt
new file mode 100644
index 0000000000..d4b5328784
--- /dev/null
+++ b/collects/tests/macro-debugger/check-requires/src-b.rkt
@@ -0,0 +1,3 @@
+#lang racket/base
+(define b 2)
+(provide b)
diff --git a/collects/tests/macro-debugger/check-requires/src-c.rkt b/collects/tests/macro-debugger/check-requires/src-c.rkt
new file mode 100644
index 0000000000..e304b62dc8
--- /dev/null
+++ b/collects/tests/macro-debugger/check-requires/src-c.rkt
@@ -0,0 +1,8 @@
+#lang racket/base
+
+(module s racket/base
+  (define cs 30)
+  (provide cs))
+
+(define c 3)
+(provide c)
diff --git a/collects/tests/macro-debugger/check-requires/use-a.rkt b/collects/tests/macro-debugger/check-requires/use-a.rkt
new file mode 100644
index 0000000000..d973a7fc54
--- /dev/null
+++ b/collects/tests/macro-debugger/check-requires/use-a.rkt
@@ -0,0 +1,7 @@
+#lang racket/base
+(require "src-a.rkt"
+         "src-b.rkt"
+         "src-c.rkt"
+         (submod "src-c.rkt" s))
+
+(void a)
diff --git a/collects/tests/macro-debugger/check-requires/use-cs.rkt b/collects/tests/macro-debugger/check-requires/use-cs.rkt
new file mode 100644
index 0000000000..73a19f8bbb
--- /dev/null
+++ b/collects/tests/macro-debugger/check-requires/use-cs.rkt
@@ -0,0 +1,7 @@
+#lang racket/base
+(require "src-a.rkt"
+         "src-b.rkt"
+         "src-c.rkt"
+         (submod "src-c.rkt" s))
+
+(void cs)