diff --git a/CHANGES.md b/CHANGES.md
index f911673d..db696257 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -2,6 +2,8 @@
 
 ## NEXT RELEASE
 
+- #562: Fix the `int32` and `int64` printers in both `Lin` and `STM` to add
+        missing `l` and `L` suffixes on literals.
 - #560: Change `Lin.{constructible,deconstructible}` from an empty variant type
         to an abstract type to get `Lin` compiling on `5.5.0+trunk` again, due
         to https://github.com/ocaml/ocaml/pull/13994 removing special handling
diff --git a/lib/STM.ml b/lib/STM.ml
index 88090b71..142972d3 100644
--- a/lib/STM.ml
+++ b/lib/STM.ml
@@ -27,8 +27,8 @@ let unit = (Unit, QCheck.Print.unit)
 let bool = (Bool, QCheck.Print.bool)
 let char = (Char, QCheck.Print.char)
 let int = (Int, QCheck.Print.int)
-let int32 = (Int32, Int32.to_string)
-let int64 = (Int64, Int64.to_string)
+let int32 = (Int32, QCheck.Print.int32)
+let int64 = (Int64, QCheck.Print.int64)
 let float = (Float, QCheck.Print.float)
 let string = (String, QCheck.Print.string)
 let bytes = (Bytes, QCheck.Print.bytes)
diff --git a/lib/lin.ml b/lib/lin.ml
index a2b5c790..912070a1 100644
--- a/lib/lin.ml
+++ b/lib/lin.ml
@@ -181,9 +181,9 @@ let int =            GenDeconstr (QCheck.int,            QCheck.Print.int,  (=))
 let int_small =      GenDeconstr (QCheck.small_int,      QCheck.Print.int,  (=))
 let int_pos =        GenDeconstr (QCheck.pos_int,        QCheck.Print.int,  (=))
 let int_bound b =    GenDeconstr (QCheck.int_bound b,    QCheck.Print.int,  (=))
-let int32 =          GenDeconstr (QCheck.int32,          Int32.to_string,   Int32.equal)
-let int64 =          GenDeconstr (QCheck.int64,          Int64.to_string,   Int64.equal)
-let nat64_small =    GenDeconstr (qcheck_nat64_small,    Int64.to_string,   Int64.equal)
+let int32 =          GenDeconstr (QCheck.int32,          QCheck.Print.int32,   Int32.equal)
+let int64 =          GenDeconstr (QCheck.int64,          QCheck.Print.int64,   Int64.equal)
+let nat64_small =    GenDeconstr (qcheck_nat64_small,    QCheck.Print.int64,   Int64.equal)
 let float =          GenDeconstr (QCheck.float,          QCheck.Print.float,  Float.equal)
 let string =         GenDeconstr (string,                QCheck.Print.string, String.equal)
 let string_small =   GenDeconstr (string_small,          QCheck.Print.string, String.equal)