diff --git a/terraform/evaluate.go b/terraform/evaluate.go
index 4bf19fefc..6dde19700 100644
--- a/terraform/evaluate.go
+++ b/terraform/evaluate.go
@@ -979,12 +979,17 @@ func getValMarks(schema *configschema.Block, val cty.Value, path cty.Path) []cty
 		if !blockS.Block.ContainsSensitive() {
 			continue
 		}
+
+		blockV := val.GetAttr(name)
+		if blockV.IsNull() || !blockV.IsKnown() {
+			continue
+		}
+
 		// Create a copy of the path, with this step added, to add to our PathValueMarks slice
 		blockPath := make(cty.Path, len(path), len(path)+1)
 		copy(blockPath, path)
 		blockPath = append(path, cty.GetAttrStep{Name: name})
 
-		blockV := val.GetAttr(name)
 		switch blockS.Nesting {
 		case configschema.NestingSingle, configschema.NestingGroup:
 			pvm = append(pvm, getValMarks(&blockS.Block, blockV, blockPath)...)
diff --git a/terraform/evaluate_test.go b/terraform/evaluate_test.go
index 7a96767f1..427b2291a 100644
--- a/terraform/evaluate_test.go
+++ b/terraform/evaluate_test.go
@@ -1,6 +1,7 @@
 package terraform
 
 import (
+	"fmt"
 	"sync"
 	"testing"
 
@@ -550,3 +551,95 @@ func evaluatorForModule(stateSync *states.SyncState, changesSync *plans.ChangesS
 		Changes: changesSync,
 	}
 }
+
+func TestMarkProviderSensitive(t *testing.T) {
+	schema := &configschema.Block{
+		Attributes: map[string]*configschema.Attribute{
+			"unsensitive": {
+				Type:     cty.String,
+				Optional: true,
+			},
+			"sensitive": {
+				Type:      cty.String,
+				Sensitive: true,
+			},
+		},
+
+		BlockTypes: map[string]*configschema.NestedBlock{
+			"list": &configschema.NestedBlock{
+				Nesting: configschema.NestingList,
+				Block: configschema.Block{
+					Attributes: map[string]*configschema.Attribute{
+						"unsensitive": {
+							Type:     cty.String,
+							Optional: true,
+						},
+						"sensitive": {
+							Type:      cty.String,
+							Sensitive: true,
+						},
+					},
+				},
+			},
+		},
+	}
+
+	for _, tc := range []struct {
+		given  cty.Value
+		expect cty.Value
+	}{
+		{
+			cty.UnknownVal(schema.ImpliedType()),
+			cty.UnknownVal(schema.ImpliedType()),
+		},
+		{
+			cty.ObjectVal(map[string]cty.Value{
+				"sensitive":   cty.UnknownVal(cty.String),
+				"unsensitive": cty.UnknownVal(cty.String),
+				"list":        cty.UnknownVal(schema.BlockTypes["list"].ImpliedType()),
+			}),
+			cty.ObjectVal(map[string]cty.Value{
+				"sensitive":   cty.UnknownVal(cty.String).Mark("sensitive"),
+				"unsensitive": cty.UnknownVal(cty.String),
+				"list":        cty.UnknownVal(schema.BlockTypes["list"].ImpliedType()),
+			}),
+		},
+		{
+			cty.ObjectVal(map[string]cty.Value{
+				"sensitive":   cty.NullVal(cty.String),
+				"unsensitive": cty.UnknownVal(cty.String),
+				"list": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"sensitive":   cty.UnknownVal(cty.String),
+						"unsensitive": cty.UnknownVal(cty.String),
+					}),
+					cty.ObjectVal(map[string]cty.Value{
+						"sensitive":   cty.NullVal(cty.String),
+						"unsensitive": cty.NullVal(cty.String),
+					}),
+				}),
+			}),
+			cty.ObjectVal(map[string]cty.Value{
+				"sensitive":   cty.NullVal(cty.String).Mark("sensitive"),
+				"unsensitive": cty.UnknownVal(cty.String),
+				"list": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"sensitive":   cty.UnknownVal(cty.String).Mark("sensitive"),
+						"unsensitive": cty.UnknownVal(cty.String),
+					}),
+					cty.ObjectVal(map[string]cty.Value{
+						"sensitive":   cty.NullVal(cty.String).Mark("sensitive"),
+						"unsensitive": cty.NullVal(cty.String),
+					}),
+				}),
+			}),
+		},
+	} {
+		t.Run(fmt.Sprintf("%#v", tc.given), func(t *testing.T) {
+			got := markProviderSensitiveAttributes(schema, tc.given)
+			if !got.RawEquals(tc.expect) {
+				t.Fatalf("\nexpected: %#v\ngot:      %#v\n", tc.expect, got)
+			}
+		})
+	}
+}