diff --git a/src/core/pp.c b/src/core/pp.c
index 253bb9a4..cbf19652 100644
--- a/src/core/pp.c
+++ b/src/core/pp.c
@@ -463,6 +463,33 @@ static int print_jdn_one(struct pretty *S, Janet x, int depth) {
             janet_buffer_push_u8(S->buffer, '}');
         }
         break;
+#ifdef JANET_INT_TYPES
+        case JANET_ABSTRACT: {
+            void *abst = janet_unwrap_abstract(x);
+            if (janet_abstract_type(abst) == &janet_s64_type) {
+                janet_buffer_ensure(S->buffer, S->buffer->count + BUFSIZE, 2);
+                int64_t s64 = janet_unwrap_s64(x);
+                int count = snprintf((char *)S->buffer->data + S->buffer->count,
+                                     BUFSIZE, "%" PRId64 ":s", s64);
+                if (count < 0) {
+                    return 1;
+                }
+                S->buffer->count += count;
+            } else if (janet_abstract_type(abst) == &janet_u64_type) {
+                janet_buffer_ensure(S->buffer, S->buffer->count + BUFSIZE, 2);
+                uint64_t u64 = janet_unwrap_u64(x);
+                int count = snprintf((char *)S->buffer->data + S->buffer->count,
+                                     BUFSIZE, "%" PRIu64 ":u", u64);
+                if (count < 0) {
+                    return 1;
+                }
+                S->buffer->count += count;
+            } else {
+                return 1;
+            }
+        }
+        break;
+#endif
         default:
             return 1;
     }
diff --git a/test/suite-pp.janet b/test/suite-pp.janet
index a75ba482..7e84adec 100644
--- a/test/suite-pp.janet
+++ b/test/suite-pp.janet
@@ -50,7 +50,8 @@
 
 # 5c364e0
 (defn check-jdn [x]
-  (assert (deep= (parse (string/format "%j" x)) x) "round trip jdn"))
+  (assert (true? (first (protect (deep= (parse (string/format "%j" x)) x))))
+          (string/format "round trip jdn: %n" x)))
 
 (check-jdn 0)
 (check-jdn nil)
@@ -60,6 +61,13 @@
 (check-jdn 12837192371923)
 (check-jdn "a string")
 (check-jdn @"a buffer")
+# Issue 1899
+(check-jdn -258:s)
+(check-jdn 3_141_592:u)
+
+# Issue 1899
+(assert-error "non-inttype abstract should fail"
+              (string/format "%j" (peg/compile 1)))
 
 # Issue 1737
 (assert (deep= "@[]" (string/format "%M" @[])))