diff --git a/compiler/pgenutil.pas b/compiler/pgenutil.pas
index b5b690685f..8ec45ce7b8 100644
--- a/compiler/pgenutil.pas
+++ b/compiler/pgenutil.pas
@@ -1342,6 +1342,17 @@ uses
                   end;
               end;
           end;
+
+        { unlink unused defs }
+        if not(result) and assigned(callerparams) then
+          begin
+            for k:=0 to callerparams.count-1 do
+              begin
+                if tsym(callerparams[k]).typ=typesym then
+                  ttypesym(callerparams[k]).typedef.typesym:=nil;
+              end;
+          end;
+
         callerparams.free;
       end;
 
diff --git a/compiler/symtype.pas b/compiler/symtype.pas
index c9e040d5bf..b89fea8ac1 100644
--- a/compiler/symtype.pas
+++ b/compiler/symtype.pas
@@ -415,6 +415,7 @@ implementation
           result:=result+GetTypeName;
       end;
 
+
     function tdef.fulltypename:string;
       begin
         result:=fullownerhierarchyname(false);
diff --git a/tests/webtbs/tw40886.pp b/tests/webtbs/tw40886.pp
new file mode 100644
index 0000000000..48c70e7d48
--- /dev/null
+++ b/tests/webtbs/tw40886.pp
@@ -0,0 +1,13 @@
+{ %opt=-gl }
+program test;
+{$modeswitch implicitfunctionspecialization}
+
+generic procedure FillChar<T>(var x; count: SizeInt; value: Byte);
+begin
+end;
+
+var v: array [0..0] of Byte;
+
+begin
+  FillChar(v, 0, 0);
+end.