diff --git a/TestSuite/Abs_Sqr_byte.pas b/TestSuite/Abs_Sqr_byte.pas
index da0145850..715d0b297 100644
--- a/TestSuite/Abs_Sqr_byte.pas
+++ b/TestSuite/Abs_Sqr_byte.pas
@@ -5,4 +5,16 @@
   var w: word := 65535;
   Assert(Sqr(w)=w*w);
   Assert(Abs(w)=w);
+  var sm: smallint := smallint.MaxValue;
+  Assert(Sqr(sm) = sm*sm);
+  var sh: shortint := shortint.MaxValue;
+  Assert(Sqr(sh) = sh*sh);
+  var lw: longword := longword.MaxValue;
+  Assert(Sqr(lw) = uint64(lw)*uint64(lw));
+  var i: integer := integer.MaxValue;
+  Assert(Sqr(i) = int64(i)*int64(i));
+  var i64: int64 := integer.MaxValue;
+  Assert(Sqr(i64) = i64*i64);
+  var ui64: uint64 := integer.MaxValue;
+  Assert(Sqr(ui64) = ui64*ui64);
 end.
\ No newline at end of file
diff --git a/bin/Lib/PABCSystem.pas b/bin/Lib/PABCSystem.pas
index 009cc26e3..29428fb81 100644
--- a/bin/Lib/PABCSystem.pas
+++ b/bin/Lib/PABCSystem.pas
@@ -8212,7 +8212,7 @@ function LogN(base, x: real) := Math.Log(x) / Math.Log(base);
 
 function Sqrt(x: real) := Math.Sqrt(x);
 
-function Sqr(x: integer): int64 := x * x;
+function Sqr(x: integer): int64 := int64(x) * int64(x);
 
 function Sqr(x: shortint): integer := x * x;
 
@@ -8222,11 +8222,11 @@ function Sqr(x: BigInteger): BigInteger := x * x;
 
 function Sqr(x: byte): integer := x * x;
 
-function Sqr(x: word): uint64 := x * x;
+function Sqr(x: word): uint64 := uint64(x) * uint64(x);
 
-function Sqr(x: longword): uint64 := x * x;
+function Sqr(x: longword): uint64 := uint64(x) * uint64(x);
 
-function Sqr(x: int64): int64 := x * x;
+function Sqr(x: int64): int64 := int64(x) * int64(x);
 
 function Sqr(x: uint64): uint64 := x * x;