diff --git a/src/plugins/flow.js b/src/plugins/flow.js
index 5022203f86..06af0a4838 100644
--- a/src/plugins/flow.js
+++ b/src/plugins/flow.js
@@ -164,7 +164,7 @@ pp.flowParseTypeParameterDeclaration = function () {
 
   this.expectRelational("<");
   while (!this.isRelational(">")) {
-    node.params.push(this.flowParseTypeAnnotatableIdentifier());
+    node.params.push(this.parseFlowTypeParam());
     if (!this.isRelational(">")) {
       this.expect(tt.comma);
     }
@@ -174,6 +174,16 @@ pp.flowParseTypeParameterDeclaration = function () {
   return this.finishNode(node, "TypeParameterDeclaration");
 };
 
+pp.parseFlowTypeParam = function () {
+  if (this.match(tt.star)) {
+    let node = this.startNode();
+    this.next();
+    return this.finishNode(node, "ExistentialTypeParam");
+  } else {
+    return this.flowParseTypeAnnotatableIdentifier();
+  }
+};
+
 pp.flowParseTypeParameterInstantiation = function () {
   let node = this.startNode(), oldInType = this.state.inType;
   node.params = [];
@@ -182,7 +192,7 @@ pp.flowParseTypeParameterInstantiation = function () {
 
   this.expectRelational("<");
   while (!this.isRelational(">")) {
-    node.params.push(this.flowParseType());
+    node.params.push(this.parseFlowTypeParam());
     if (!this.isRelational(">")) {
       this.expect(tt.comma);
     }
diff --git a/src/tokenizer/context.js b/src/tokenizer/context.js
index 7b7236e500..a8e592da6e 100644
--- a/src/tokenizer/context.js
+++ b/src/tokenizer/context.js
@@ -56,6 +56,8 @@ tt.parenR.updateContext = tt.braceR.updateContext = function () {
 };
 
 tt.name.updateContext = function (prevType) {
+  this.state.exprAllowed = false;
+  
   if (prevType === tt._let || prevType === tt._const || prevType === tt._var) {
     if (lineBreak.test(this.input.slice(this.state.end))) {
       this.state.exprAllowed = true;
diff --git a/test/fixtures/flow/type-annotations/existential-type-param/actual.js b/test/fixtures/flow/type-annotations/existential-type-param/actual.js
new file mode 100644
index 0000000000..83f6d6f432
--- /dev/null
+++ b/test/fixtures/flow/type-annotations/existential-type-param/actual.js
@@ -0,0 +1 @@
+type Maybe<T> = _Maybe<T, *>;
diff --git a/test/fixtures/flow/type-annotations/existential-type-param/expected.json b/test/fixtures/flow/type-annotations/existential-type-param/expected.json
new file mode 100644
index 0000000000..a412ffa9a8
--- /dev/null
+++ b/test/fixtures/flow/type-annotations/existential-type-param/expected.json
@@ -0,0 +1,177 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 29,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 29
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 29,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 29
+      }
+    },
+    "sourceType": "module",
+    "body": [
+      {
+        "type": "TypeAlias",
+        "start": 0,
+        "end": 29,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 29
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 5,
+          "end": 10,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 5
+            },
+            "end": {
+              "line": 1,
+              "column": 10
+            }
+          },
+          "name": "Maybe"
+        },
+        "typeParameters": {
+          "type": "TypeParameterDeclaration",
+          "start": 10,
+          "end": 13,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 10
+            },
+            "end": {
+              "line": 1,
+              "column": 13
+            }
+          },
+          "params": [
+            {
+              "type": "Identifier",
+              "start": 11,
+              "end": 12,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 11
+                },
+                "end": {
+                  "line": 1,
+                  "column": 12
+                }
+              },
+              "name": "T"
+            }
+          ]
+        },
+        "right": {
+          "type": "GenericTypeAnnotation",
+          "start": 16,
+          "end": 28,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 16
+            },
+            "end": {
+              "line": 1,
+              "column": 28
+            }
+          },
+          "typeParameters": {
+            "type": "TypeParameterInstantiation",
+            "start": 22,
+            "end": 28,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 22
+              },
+              "end": {
+                "line": 1,
+                "column": 28
+              }
+            },
+            "params": [
+              {
+                "type": "Identifier",
+                "start": 23,
+                "end": 24,
+                "loc": {
+                  "start": {
+                    "line": 1,
+                    "column": 23
+                  },
+                  "end": {
+                    "line": 1,
+                    "column": 24
+                  }
+                },
+                "name": "T"
+              },
+              {
+                "type": "ExistentialTypeParam",
+                "start": 26,
+                "end": 27,
+                "loc": {
+                  "start": {
+                    "line": 1,
+                    "column": 26
+                  },
+                  "end": {
+                    "line": 1,
+                    "column": 27
+                  }
+                }
+              }
+            ]
+          },
+          "id": {
+            "type": "Identifier",
+            "start": 16,
+            "end": 22,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 16
+              },
+              "end": {
+                "line": 1,
+                "column": 22
+              }
+            },
+            "name": "_Maybe"
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file