diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index 53ef54431e..2dd86d7694 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -1453,8 +1453,12 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
     let origF = f
     var f = if prev == nil: f else: prev
 
-    let roota = a.skipGenericAlias
-    let rootf = f.skipGenericAlias
+    let deptha = a.genericAliasDepth()
+    let depthf = f.genericAliasDepth()
+    let skipBoth = deptha == depthf and (a.len > 0 and f.len > 0 and a.base != f.base)
+
+    let roota = if skipBoth or deptha > depthf: a.skipGenericAlias else: a
+    let rootf = if skipBoth or depthf > deptha: f.skipGenericAlias else: f
 
     if a.kind == tyGenericInst:
       if roota.base == rootf.base:
diff --git a/compiler/types.nim b/compiler/types.nim
index 41fd18bfe7..3d620b1f6f 100644
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -1184,6 +1184,13 @@ proc sameChildrenAux(a, b: PType, c: var TSameTypeClosure): bool =
 proc isGenericAlias*(t: PType): bool =
   return t.kind == tyGenericInst and t.lastSon.kind == tyGenericInst
 
+proc genericAliasDepth*(t: PType): int =
+  result = 0
+  var it = t
+  while it.isGenericAlias:
+    it = it.lastSon
+    inc result
+
 proc skipGenericAlias*(t: PType): PType =
   return if t.isGenericAlias: t.lastSon else: t
 
diff --git a/tests/generics/t21742.nim b/tests/generics/t21742.nim
new file mode 100644
index 0000000000..c49c8ee97c
--- /dev/null
+++ b/tests/generics/t21742.nim
@@ -0,0 +1,10 @@
+type
+  Foo[T] = object
+    x:T
+  Bar[T,R] = Foo[T]
+  Baz = Bar[int,float]
+
+proc qux[T,R](x: Bar[T,R]) = discard
+
+var b:Baz
+b.qux()
\ No newline at end of file