diff --git a/configure b/configure
index 7d26355df..93b899015 100755
--- a/configure
+++ b/configure
@@ -59,7 +59,7 @@ package_out_of_tree() {
 
 readonly gerbil_version="$(git describe --tags --always)"
 readonly gerbil_targets=""
-readonly default_gambit_tag=24201248effa23d5017be4992b5b9879e4cd3a4c
+readonly default_gambit_tag=8b18ab69504c2d41301f7fec16a5350db717a20e
 readonly default_gambit_config="--enable-targets=${gerbil_targets} --enable-single-host --enable-dynamic-clib --enable-default-runtime-options=tE8,f8,-8 --enable-trust-c-tco"
 prefix="/opt/gerbil"
 readonly cflags_opt="-foptimize-sibling-calls"
diff --git a/doc/reference/gerbil/expander/utilities.md b/doc/reference/gerbil/expander/utilities.md
index e7ba9b3fc..1d751421a 100644
--- a/doc/reference/gerbil/expander/utilities.md
+++ b/doc/reference/gerbil/expander/utilities.md
@@ -1,134 +1,133 @@
 ## Utilities
 
 ### stx-boolean?
-```
+```scheme
 (stx-boolean? ...)
 ```
 
 Please document me!
 
 ### stx-keyword?
-```
+```scheme
 (stx-keyword? ...)
 ```
 
 Please document me!
 
 ### stx-char?
-```
+```scheme
 (stx-char? ...)
 ```
 
 Please document me!
 
 ### stx-number?
-```
+```scheme
 (stx-number? ...)
 ```
 
 Please document me!
 
 ### stx-fixnum?
-```
+```scheme
 (stx-fixnum? ...)
 ```
 
 Please document me!
 
 ### stx-string?
-```
+```scheme
 (stx-string? ...)
 ```
 
 Please document me!
 
 ### stx-null?
-```
+```scheme
 (stx-null? ...)
 ```
 
 Please document me!
 
 ### stx-pair?
-```
+```scheme
 (stx-pair? ...)
 ```
 
 Please document me!
 
 ### stx-pair/null?
-```
+```scheme
 (stx-pair/null? ...)
 ```
 
 Please document me!
 
 ### stx-list?
-```
+```scheme
 (stx-list? ...)
 ```
 
 Please document me!
 
 ### stx-box?
-```
+```scheme
 (stx-box? ...)
 ```
 
 Please document me!
 
 ### stx-vector?
-```
+```scheme
 (stx-vector? ...)
 ```
 
 Please document me!
 
 ### stx-datum?
-```
+```scheme
 (stx-datum? ...)
 ```
 
 Please document me!
 
 ### stx-eq?
-```
+```scheme
 (stx-eq? ...)
 ```
 
 Please document me!
 
 ### stx-eqv?
-```
+```scheme
 (stx-eqv? ...)
 ```
 
 Please document me!
 
 ### stx-equal?
-```
+```scheme
 (stx-equal? ...)
 ```
 
 Please document me!
 
 ### stx-false?
-```
+```scheme
 (stx-false? ...)
 ```
 
 Please document me!
 
 ### stx-e
-```
+```scheme
 (stx-e ...)
 ```
 
 Please document me!
 
 ### stx-source
-
-```
+```scheme
 (stx-source stx) -> locat | #f
   stx := syntax
 ```
@@ -140,124 +139,132 @@ The `locat` structure includes the container and filepos, accessed by `##locat-c
 
 ### stx-wrap-source
 
-```
+```scheme
 (stx-wrap-source stx src) -> syntax
   stx := any
   src := locat
 ```
 :::
 
-Produces a new syntax object with source location `src` if `stx` is not wrapped as an AST already, otherwise returns `stx` unchanged.
+Produces a new syntax object with source location `src`
+if `stx` is not wrapped as an AST already, otherwise returns `stx` unchanged.
 
-The `locat` structure can be constructed with `(##make-locat container filepos)`, where a filepos can be constructed with `(##make-filepos line col off)`.
+The `locat` structure can be constructed with
+`(##make-locat container filepos filepos-end)`, where:
+  - `container` is a string denoting a file path, or a list containing
+    a symbol denoting the provenance (string, port, etc.).
+  - `filepos` can be constructed with `(##make-filepos line col off)`.
+  - `filepos-end` can be `#f` if the location is a position, or
+    a number similar to `filepos` indicating the end position (not included)
+    if the location is a range.
 
 ### stx-car
-```
+```scheme
 (stx-car ...)
 ```
 
 Please document me!
 
 ### stx-cdr
-```
+```scheme
 (stx-cdr ...)
 ```
 
 Please document me!
 
 ### stx-length
-```
+```scheme
 (stx-length ...)
 ```
 
 Please document me!
 
 ### stx-for-each
-```
+```scheme
 (stx-for-each ...)
 ```
 
 Please document me!
 
 ### stx-map
-```
+```scheme
 (stx-map ...)
 ```
 
 Please document me!
 
 ### stx-foldl
-```
+```scheme
 (stx-foldl ...)
 ```
 
 Please document me!
 
 ### stx-foldr
-```
+```scheme
 (stx-foldr ...)
 ```
 
 Please document me!
 
 ### stx-reverse
-```
+```scheme
 (stx-reverse ...)
 ```
 
 Please document me!
 
 ### stx-last
-```
+```scheme
 (stx-last ...)
 ```
 
 Please document me!
 
 ### stx-last-pair
-```
+```scheme
 (stx-last-pair ...)
 ```
 
 Please document me!
 
 ### stx-list-tail
-```
+```scheme
 (stx-list-tail ...)
 ```
 
 Please document me!
 
 ### stx-list-ref
-```
+```scheme
 (stx-list-ref ...)
 ```
 
 Please document me!
 
 ### stx-andmap
-```
+```scheme
 (stx-andmap ...)
 ```
 
 Please document me!
 
 ### stx-ormap
-```
+```scheme
 (stx-ormap ...)
 ```
 
 Please document me!
 
 ### stx-plist?
-```
+```scheme
 (stx-plist? ...)
 ```
 
 Please document me!
 
 ### stx-getq
-```
+```scheme
 (stx-getq ...)
 ```
 
diff --git a/src/std/parser/base.ss b/src/std/parser/base.ss
index 6e8a7302a..d32c55557 100644
--- a/src/std/parser/base.ss
+++ b/src/std/parser/base.ss
@@ -76,10 +76,10 @@
              (##port-name port)))
            (filepos
             (##make-filepos line col off)))
-      (##make-locat container filepos))))
+      (##make-locat container filepos #f))))
 
 (def (display-location loc (port (current-output-port)))
-  (##display-locat (location->source-location loc)  #t port))
+  (##display-locat (location->source-location loc) #t port))
 
 ;; location [start end]
 (def (location-delta start end)