diff --git a/lib/srfi/145.sld b/lib/srfi/145.sld
index 66d1b43b..8023dc89 100644
--- a/lib/srfi/145.sld
+++ b/lib/srfi/145.sld
@@ -1,30 +1,23 @@
-
 (define-library (srfi 145)
   (export assume)
   (import (scheme base))
   (cond-expand
-   (elide-assumptions
-    (begin
-      (define-syntax assume
-        (syntax-rules ()
-          ((assume expression objs ...)
-           expression)
-          ((assume)
-           (syntax-error "assume requires an expression"))))))
-   (else
-    (begin
-      (define-syntax assume
-        (syntax-rules ()
-          ((assume expression objs ...)
-           (or expression
-               (fatal-error "invalid assumption" 'expression objs ...)))
-          ((assume)
-           (syntax-error "assume requires an expression")))))))
-  (cond-expand
-   (debug
-    (begin
-      (define fatal-error error)))
-   (else
-    (begin
-      (define (fatal-error message . objs)
-        (car 0))))))
+    ((or elide-assumptions
+         (and (not assumptions)
+              (not debug)))
+     (begin
+       (define-syntax assume
+         (syntax-rules ()
+           ((assume expression objs ...)
+            expression)
+           ((assume)
+            (syntax-error "assume requires an expression"))))))
+    (else
+     (begin
+       (define-syntax assume
+         (syntax-rules ()
+           ((assume expression objs ...)
+            (or expression
+                (error "invalid assumption" 'expression objs ...)))
+           ((assume)
+            (syntax-error "assume requires an expression"))))))))