diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7f5f8b2b..130ce730 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ Bug Fixes
 
 - Fix `read-line` to remove trailing carriage return and/or newline characters. Thanks to wasamasa for the bug report!
 - String ports created by `open-input-string` returned an extra garbage byte. This has been fixed by a patch from wasamasa.
+- Prevent segfaults when allocating large strings using `make-string`.
 - Added a fix from wasamasa to escape double quotation marks in strings when output via `write`.
 
 ## 0.6.2 - August 25, 2017
diff --git a/scheme/base.sld b/scheme/base.sld
index c7e31ebb..47af273b 100644
--- a/scheme/base.sld
+++ b/scheme/base.sld
@@ -938,47 +938,44 @@
                   (return #f)))
               objs)
               #t))))
+
     (define (string . chars)
       (list->string chars))
+
     (define (make-string k . fill)
-      (let ((fill* (if (null? fill)
-                      '(#\space)
-                      fill)))
-        (list->string
-          (apply make-list (cons k fill*)))))
-;    (define (make-string k . fill)
-;      (Cyc-make-string k (if (null? fill) #\space (car fill))))
-;    (define-c Cyc-make-string
-;      "(void *data, int argc, closure _, object k, object count, object fill)"
-;      " object s = NULL;
-;        Cyc_check_int(data, count);
-;        // TODO: type check fill
-;        char c = obj_obj2char(fill);
-;        int len = obj_obj2int(count);
-;        if (len >= MAX_STACK_OBJ) {
-;          int heap_grown;
-;          s = gc_alloc(((gc_thread_data *)data)->heap, 
-;                       sizeof(string_type) + len + 1,
-;                       boolean_f, // OK to populate manually over here
-;                       (gc_thread_data *)data, 
-;                       &heap_grown);
-;          ((string_type *) s)->hdr.mark = ((gc_thread_data *)data)->gc_alloc_color;
-;          ((string_type *) s)->hdr.grayed = 0;
-;          ((string_type *) s)->tag = string_tag; 
-;          ((string_type *) s)->len = len;
-;          ((string_type *) s)->str = (((char *)s) + sizeof(string_type));
-;        } else {
-;          s = alloca(sizeof(string_type));
-;          ((string_type *)s)->hdr.mark = gc_color_red; 
-;          ((string_type *)s)->hdr.grayed = 0;
-;          ((string_type *)s)->tag = string_tag; 
-;          ((string_type *)s)->len = len;
-;          ((string_type *)s)->str = alloca(sizeof(char) * (len + 1));
-;        }
-;        memset(((string_type *)s)->str, c, len);
-;        ((string_type *)s)->str[len] = '\\0';
-;        return_closcall1(data, k, &s);
-;      ")
+      (Cyc-make-string k (if (null? fill) #\space (car fill))))
+
+    (define-c Cyc-make-string
+      "(void *data, int argc, closure _, object k, object count, object fill)"
+      " object s = NULL;
+        Cyc_check_int(data, count);
+        char c = obj_obj2char(fill);
+        int len = obj_obj2int(count);
+        if (len >= MAX_STACK_OBJ) {
+          int heap_grown;
+          s = gc_alloc(((gc_thread_data *)data)->heap, 
+                       sizeof(string_type) + len + 1,
+                       boolean_f, // OK to populate manually over here
+                       (gc_thread_data *)data, 
+                       &heap_grown);
+          ((string_type *) s)->hdr.mark = ((gc_thread_data *)data)->gc_alloc_color;
+          ((string_type *) s)->hdr.grayed = 0;
+          ((string_type *) s)->tag = string_tag; 
+          ((string_type *) s)->len = len;
+          ((string_type *) s)->str = (((char *)s) + sizeof(string_type));
+        } else {
+          s = alloca(sizeof(string_type));
+          ((string_type *)s)->hdr.mark = gc_color_red; 
+          ((string_type *)s)->hdr.grayed = 0;
+          ((string_type *)s)->tag = string_tag; 
+          ((string_type *)s)->len = len;
+          ((string_type *)s)->str = alloca(sizeof(char) * (len + 1));
+        }
+        memset(((string_type *)s)->str, c, len);
+        ((string_type *)s)->str[len] = '\\0';
+        return_closcall1(data, k, s);
+      ")
+
     (define-syntax parameterize
       (syntax-rules ()
         ((parameterize