diff --git a/src/services/utilities.ts b/src/services/utilities.ts
index b67c8da5420..3d503bff659 100644
--- a/src/services/utilities.ts
+++ b/src/services/utilities.ts
@@ -758,7 +758,7 @@ namespace ts {
         if (isClassDeclaration(node)) {
             // for class and function declarations, use the `default` modifier
             // when the declaration is unnamed.
-            const defaultModifier = find(node.modifiers!, isDefaultModifier);
+            const defaultModifier = node.modifiers && find(node.modifiers, isDefaultModifier);
             if (defaultModifier) return defaultModifier;
         }
         if (isClassExpression(node)) {
diff --git a/tests/baselines/reference/quickInfoDisplayPartsClassDefaultAnonymous.baseline b/tests/baselines/reference/quickInfoDisplayPartsClassDefaultAnonymous.baseline
new file mode 100644
index 00000000000..6f0e960d874
--- /dev/null
+++ b/tests/baselines/reference/quickInfoDisplayPartsClassDefaultAnonymous.baseline
@@ -0,0 +1,76 @@
+[
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultAnonymous.ts",
+      "position": 0,
+      "name": "1"
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultAnonymous.ts",
+      "position": 7,
+      "name": "2"
+    },
+    "quickInfo": {
+      "kind": "class",
+      "kindModifiers": "export",
+      "textSpan": {
+        "start": 7,
+        "length": 7
+      },
+      "displayParts": [
+        {
+          "text": "class",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "default",
+          "kind": "className"
+        }
+      ],
+      "documentation": []
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultAnonymous.ts",
+      "position": 15,
+      "name": "3"
+    },
+    "quickInfo": {
+      "kind": "class",
+      "kindModifiers": "export",
+      "textSpan": {
+        "start": 15,
+        "length": 5
+      },
+      "displayParts": [
+        {
+          "text": "class",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "default",
+          "kind": "className"
+        }
+      ],
+      "documentation": []
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultAnonymous.ts",
+      "position": 21,
+      "name": "4"
+    }
+  }
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/quickInfoDisplayPartsClassDefaultNamed.baseline b/tests/baselines/reference/quickInfoDisplayPartsClassDefaultNamed.baseline
new file mode 100644
index 00000000000..cdaaee1e1c2
--- /dev/null
+++ b/tests/baselines/reference/quickInfoDisplayPartsClassDefaultNamed.baseline
@@ -0,0 +1,106 @@
+[
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultNamed.ts",
+      "position": 0,
+      "name": "1"
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultNamed.ts",
+      "position": 7,
+      "name": "2"
+    },
+    "quickInfo": {
+      "kind": "class",
+      "kindModifiers": "export",
+      "textSpan": {
+        "start": 7,
+        "length": 7
+      },
+      "displayParts": [
+        {
+          "text": "class",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "C",
+          "kind": "className"
+        }
+      ],
+      "documentation": []
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultNamed.ts",
+      "position": 15,
+      "name": "3"
+    },
+    "quickInfo": {
+      "kind": "class",
+      "kindModifiers": "export",
+      "textSpan": {
+        "start": 15,
+        "length": 5
+      },
+      "displayParts": [
+        {
+          "text": "class",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "C",
+          "kind": "className"
+        }
+      ],
+      "documentation": []
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultNamed.ts",
+      "position": 21,
+      "name": "4"
+    },
+    "quickInfo": {
+      "kind": "class",
+      "kindModifiers": "export",
+      "textSpan": {
+        "start": 21,
+        "length": 1
+      },
+      "displayParts": [
+        {
+          "text": "class",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "C",
+          "kind": "className"
+        }
+      ],
+      "documentation": []
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultNamed.ts",
+      "position": 23,
+      "name": "5"
+    }
+  }
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/quickInfoDisplayPartsClassIncomplete.baseline b/tests/baselines/reference/quickInfoDisplayPartsClassIncomplete.baseline
new file mode 100644
index 00000000000..93919d9b5bf
--- /dev/null
+++ b/tests/baselines/reference/quickInfoDisplayPartsClassIncomplete.baseline
@@ -0,0 +1,39 @@
+[
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassIncomplete.ts",
+      "position": 0,
+      "name": "1"
+    },
+    "quickInfo": {
+      "kind": "class",
+      "kindModifiers": "",
+      "textSpan": {
+        "start": 0,
+        "length": 5
+      },
+      "displayParts": [
+        {
+          "text": "class",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "__missing",
+          "kind": "className"
+        }
+      ],
+      "documentation": []
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsClassIncomplete.ts",
+      "position": 6,
+      "name": "2"
+    }
+  }
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/quickInfoDisplayPartsFunctionIncomplete.baseline b/tests/baselines/reference/quickInfoDisplayPartsFunctionIncomplete.baseline
new file mode 100644
index 00000000000..829dd84f076
--- /dev/null
+++ b/tests/baselines/reference/quickInfoDisplayPartsFunctionIncomplete.baseline
@@ -0,0 +1,204 @@
+[
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsFunctionIncomplete.ts",
+      "position": 0,
+      "name": "1"
+    },
+    "quickInfo": {
+      "kind": "function",
+      "kindModifiers": "",
+      "textSpan": {
+        "start": 0,
+        "length": 8
+      },
+      "displayParts": [
+        {
+          "text": "function",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "(Missing)",
+          "kind": "functionName"
+        },
+        {
+          "text": "(",
+          "kind": "punctuation"
+        },
+        {
+          "text": "param",
+          "kind": "parameterName"
+        },
+        {
+          "text": ":",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "string",
+          "kind": "keyword"
+        },
+        {
+          "text": ")",
+          "kind": "punctuation"
+        },
+        {
+          "text": ":",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "void",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "(",
+          "kind": "punctuation"
+        },
+        {
+          "text": "+",
+          "kind": "operator"
+        },
+        {
+          "text": "1",
+          "kind": "numericLiteral"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "overload",
+          "kind": "text"
+        },
+        {
+          "text": ")",
+          "kind": "punctuation"
+        }
+      ],
+      "documentation": []
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsFunctionIncomplete.ts",
+      "position": 9,
+      "name": "2"
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsFunctionIncomplete.ts",
+      "position": 30,
+      "name": "3"
+    },
+    "quickInfo": {
+      "kind": "function",
+      "kindModifiers": "",
+      "textSpan": {
+        "start": 30,
+        "length": 8
+      },
+      "displayParts": [
+        {
+          "text": "function",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "(Missing)",
+          "kind": "functionName"
+        },
+        {
+          "text": "(",
+          "kind": "punctuation"
+        },
+        {
+          "text": "param",
+          "kind": "parameterName"
+        },
+        {
+          "text": ":",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "string",
+          "kind": "keyword"
+        },
+        {
+          "text": ")",
+          "kind": "punctuation"
+        },
+        {
+          "text": ":",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "void",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "(",
+          "kind": "punctuation"
+        },
+        {
+          "text": "+",
+          "kind": "operator"
+        },
+        {
+          "text": "1",
+          "kind": "numericLiteral"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "overload",
+          "kind": "text"
+        },
+        {
+          "text": ")",
+          "kind": "punctuation"
+        }
+      ],
+      "documentation": []
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoDisplayPartsFunctionIncomplete.ts",
+      "position": 39,
+      "name": "4"
+    }
+  }
+]
\ No newline at end of file
diff --git a/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultAnonymous.ts b/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultAnonymous.ts
new file mode 100644
index 00000000000..01aadf05c81
--- /dev/null
+++ b/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultAnonymous.ts
@@ -0,0 +1,6 @@
+/// <reference path='fourslash.ts'/>
+
+/////*1*/export /*2*/default /*3*/class /*4*/ {
+////}
+
+verify.baselineQuickInfo();
\ No newline at end of file
diff --git a/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultNamed.ts b/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultNamed.ts
new file mode 100644
index 00000000000..d8ea23dd073
--- /dev/null
+++ b/tests/cases/fourslash/quickInfoDisplayPartsClassDefaultNamed.ts
@@ -0,0 +1,6 @@
+/// <reference path='fourslash.ts'/>
+
+/////*1*/export /*2*/default /*3*/class /*4*/C /*5*/ {
+////}
+
+verify.baselineQuickInfo();
\ No newline at end of file
diff --git a/tests/cases/fourslash/quickInfoDisplayPartsClassIncomplete.ts b/tests/cases/fourslash/quickInfoDisplayPartsClassIncomplete.ts
new file mode 100644
index 00000000000..4313c7345fb
--- /dev/null
+++ b/tests/cases/fourslash/quickInfoDisplayPartsClassIncomplete.ts
@@ -0,0 +1,6 @@
+/// <reference path='fourslash.ts'/>
+
+/////*1*/class /*2*/ {
+////}
+
+verify.baselineQuickInfo();
\ No newline at end of file
diff --git a/tests/cases/fourslash/quickInfoDisplayPartsFunctionIncomplete.ts b/tests/cases/fourslash/quickInfoDisplayPartsFunctionIncomplete.ts
new file mode 100644
index 00000000000..0eafe8f9e6f
--- /dev/null
+++ b/tests/cases/fourslash/quickInfoDisplayPartsFunctionIncomplete.ts
@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts'/>
+
+/////*1*/function /*2*/(param: string) {
+////}\
+/////*3*/function /*4*/ {
+////}\
+
+verify.baselineQuickInfo();
\ No newline at end of file