diff --git a/terraform/eval_for_each.go b/terraform/eval_for_each.go
index 23ba388b5..1db1c3fad 100644
--- a/terraform/eval_for_each.go
+++ b/terraform/eval_for_each.go
@@ -50,7 +50,7 @@ func evaluateResourceForEachExpressionKnown(expr hcl.Expression, ctx EvalContext
 			Subject:  expr.Range().Ptr(),
 		})
 		return nil, true, diags
-	case !forEachVal.IsWhollyKnown():
+	case !forEachVal.IsKnown():
 		return map[string]cty.Value{}, false, diags
 	}
 
@@ -74,6 +74,11 @@ func evaluateResourceForEachExpressionKnown(expr hcl.Expression, ctx EvalContext
 			})
 			return nil, true, diags
 		}
+
+		// For sets, we need to recursively check ...and add reasoning why this works here
+		if !forEachVal.IsWhollyKnown() {
+			return map[string]cty.Value{}, false, diags
+		}
 	}
 
 	// If the map is empty ({}), return an empty map, because cty will return nil when representing {} AsValueMap
diff --git a/terraform/terraform_test.go b/terraform/terraform_test.go
index 3a9d88c0b..0d8cc0900 100644
--- a/terraform/terraform_test.go
+++ b/terraform/terraform_test.go
@@ -553,7 +553,25 @@ aws_instance.foo["e30a7edcc42a846684f2a4eea5f3cd261d33c46d"]:
   ID = foo
   provider = provider.aws
   foo = foo
-  type = aws_instance`
+  type = aws_instance
+aws_instance.one["a"]:
+  ID = foo
+  provider = provider.aws
+aws_instance.one["b"]:
+  ID = foo
+  provider = provider.aws
+aws_instance.two["a"]:
+  ID = foo
+  provider = provider.aws
+
+  Dependencies:
+    aws_instance.one
+aws_instance.two["b"]:
+  ID = foo
+  provider = provider.aws
+
+  Dependencies:
+    aws_instance.one`
 const testTerraformApplyMinimalStr = `
 aws_instance.bar:
   ID = foo
diff --git a/terraform/testdata/plan-for-each-unknown-value/main.tf b/terraform/testdata/plan-for-each-unknown-value/main.tf
index 2b26dbd1f..933ed5f4c 100644
--- a/terraform/testdata/plan-for-each-unknown-value/main.tf
+++ b/terraform/testdata/plan-for-each-unknown-value/main.tf
@@ -9,3 +9,12 @@ resource "aws_instance" "foo" {
     )
   foo = "foo"
 }
+
+# referencing another resource, which means it has some unknown values in it
+resource "aws_instance" "one" {
+  for_each = toset(["a", "b"])
+}
+
+resource "aws_instance" "two" {
+  for_each = aws_instance.one
+}