diff --git a/.gitattributes b/.gitattributes
index 4bcfd43c6a..3e7dbadd89 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -10213,6 +10213,7 @@ tests/tbs/tb0602.pp svneol=native#text/plain
 tests/tbs/tb0603.pp svneol=native#text/pascal
 tests/tbs/tb0604.pp svneol=native#text/pascal
 tests/tbs/tb0605.pp svneol=native#text/pascal
+tests/tbs/tb0606.pp svneol=native#text/pascal
 tests/tbs/tb205.pp svneol=native#text/plain
 tests/tbs/tbs0594.pp svneol=native#text/pascal
 tests/tbs/ub0060.pp svneol=native#text/plain
@@ -13900,6 +13901,7 @@ tests/webtbs/tw25551.pp svneol=native#text/plain
 tests/webtbs/tw25598.pp svneol=native#text/plain
 tests/webtbs/tw25600.pp svneol=native#text/pascal
 tests/webtbs/tw25603.pp svneol=native#text/pascal
+tests/webtbs/tw25604.pp svneol=native#text/pascal
 tests/webtbs/tw25605.pp svneol=native#text/pascal
 tests/webtbs/tw2561.pp svneol=native#text/plain
 tests/webtbs/tw25610.pp -text svneol=native#text/plain
diff --git a/compiler/nmat.pas b/compiler/nmat.pas
index e9a1d37855..4af8ff48da 100644
--- a/compiler/nmat.pas
+++ b/compiler/nmat.pas
@@ -197,6 +197,14 @@ implementation
          result:=nil;
          typecheckpass(left);
          typecheckpass(right);
+
+         { avoid any problems with type parameters later on }
+         if is_typeparam(left.resultdef) or is_typeparam(right.resultdef) then
+           begin
+             resultdef:=cundefinedtype;
+             exit;
+           end;
+
          set_varstate(left,vs_read,[vsf_must_be_valid]);
          set_varstate(right,vs_read,[vsf_must_be_valid]);
          if codegenerror then
@@ -644,6 +652,14 @@ implementation
          result:=nil;
          typecheckpass(left);
          typecheckpass(right);
+
+         { avoid any problems with type parameters later on }
+         if is_typeparam(left.resultdef) or is_typeparam(right.resultdef) then
+           begin
+             resultdef:=cundefinedtype;
+             exit;
+           end;
+
          set_varstate(right,vs_read,[vsf_must_be_valid]);
          set_varstate(left,vs_read,[vsf_must_be_valid]);
          if codegenerror then
@@ -818,6 +834,14 @@ implementation
       begin
          result:=nil;
          typecheckpass(left);
+
+         { avoid any problems with type parameters later on }
+         if is_typeparam(left.resultdef) then
+           begin
+             resultdef:=cundefinedtype;
+             exit;
+           end;
+
          set_varstate(left,vs_read,[vsf_must_be_valid]);
          if codegenerror then
            exit;
@@ -968,6 +992,14 @@ implementation
       begin
         result:=nil;
         typecheckpass(left);
+
+        { avoid any problems with type parameters later on }
+        if is_typeparam(left.resultdef) then
+          begin
+            resultdef:=cundefinedtype;
+            exit;
+          end;
+
         set_varstate(left,vs_read,[vsf_must_be_valid]);
         if codegenerror then
           exit;
@@ -1144,6 +1176,14 @@ implementation
       begin
          result:=nil;
          typecheckpass(left);
+
+         { avoid any problems with type parameters later on }
+         if is_typeparam(left.resultdef) then
+           begin
+             resultdef:=cundefinedtype;
+             exit;
+           end;
+
          set_varstate(left,vs_read,[vsf_must_be_valid]);
          if codegenerror then
            exit;
diff --git a/tests/tbs/tb0606.pp b/tests/tbs/tb0606.pp
new file mode 100644
index 0000000000..b8bd24c34e
--- /dev/null
+++ b/tests/tbs/tb0606.pp
@@ -0,0 +1,32 @@
+{ %NORUN }
+
+program tb0606;
+
+{$mode delphi}
+
+type
+  TTest<T> = class
+    procedure Test;
+  end;
+
+procedure TTest<T>.Test;
+var
+  r: T;
+  i: LongInt;
+begin
+  r := i div r;
+  r := r div i;
+  r := i mod r;
+  r := r mod i;
+  r := i shl r;
+  r := r shl i;
+  r := i shr r;
+  r := r shr i;
+  r := - r;
+  r := not r;
+  r := + r;
+end;
+
+begin
+
+end.
diff --git a/tests/webtbs/tw25604.pp b/tests/webtbs/tw25604.pp
new file mode 100644
index 0000000000..b117977b32
--- /dev/null
+++ b/tests/webtbs/tw25604.pp
@@ -0,0 +1,24 @@
+{ %NORUN }
+
+program tw25604;
+
+{$MODE DELPHI}
+
+type
+  TA<T> = class
+  private
+    F1, F2: T;
+    procedure Foo;
+  end;
+
+procedure TA<T>.Foo;
+var
+  b: Integer;
+begin
+  b := (b and F1) shr F2; // pass
+  b := (b and not F1) or (b shl F2); // Error: Operator is not overloaded: "LongInt" shl "<undefined type>"
+end;
+
+begin
+end.
+