diff --git a/Godeps/Godeps.json b/Godeps/Godeps.json
index dd820e1ee9..0274ff8bcd 100644
--- a/Godeps/Godeps.json
+++ b/Godeps/Godeps.json
@@ -685,11 +685,11 @@
 		},
 		{
 			"ImportPath": "github.com/hashicorp/hil",
-			"Rev": "0457360d54ca4d081a769eaa1617e0462153fd70"
+			"Rev": "1586b586f59cfa528a751d4a62be88910d34e6e9"
 		},
 		{
 			"ImportPath": "github.com/hashicorp/hil/ast",
-			"Rev": "0457360d54ca4d081a769eaa1617e0462153fd70"
+			"Rev": "1586b586f59cfa528a751d4a62be88910d34e6e9"
 		},
 		{
 			"ImportPath": "github.com/hashicorp/logutils",
diff --git a/vendor/github.com/hashicorp/hil/builtins.go b/vendor/github.com/hashicorp/hil/builtins.go
index 0afa3e0278..8c8a34803c 100644
--- a/vendor/github.com/hashicorp/hil/builtins.go
+++ b/vendor/github.com/hashicorp/hil/builtins.go
@@ -22,6 +22,7 @@ func registerBuiltins(scope *ast.BasicScope) *ast.BasicScope {
 	scope.FuncMap["__builtin_IntToFloat"] = builtinIntToFloat()
 	scope.FuncMap["__builtin_IntToString"] = builtinIntToString()
 	scope.FuncMap["__builtin_StringToInt"] = builtinStringToInt()
+	scope.FuncMap["__builtin_StringToFloat"] = builtinStringToFloat()
 
 	// Math operations
 	scope.FuncMap["__builtin_IntMath"] = builtinIntMath()
@@ -142,3 +143,18 @@ func builtinStringToInt() ast.Function {
 		},
 	}
 }
+
+func builtinStringToFloat() ast.Function {
+	return ast.Function{
+		ArgTypes:   []ast.Type{ast.TypeString},
+		ReturnType: ast.TypeFloat,
+		Callback: func(args []interface{}) (interface{}, error) {
+			v, err := strconv.ParseFloat(args[0].(string), 64)
+			if err != nil {
+				return nil, err
+			}
+
+			return v, nil
+		},
+	}
+}
diff --git a/vendor/github.com/hashicorp/hil/check_types.go b/vendor/github.com/hashicorp/hil/check_types.go
index afffffcf1c..3d157c597d 100644
--- a/vendor/github.com/hashicorp/hil/check_types.go
+++ b/vendor/github.com/hashicorp/hil/check_types.go
@@ -251,7 +251,7 @@ func (tc *typeCheckConcat) TypeCheck(v *TypeCheck) (ast.Node, error) {
 			}
 
 			return nil, fmt.Errorf(
-				"argument %d must be a string", i+1)
+				"output of an HIL expression must be a string (argument %d is %s)", i+1, t)
 		}
 	}
 
diff --git a/vendor/github.com/hashicorp/hil/eval.go b/vendor/github.com/hashicorp/hil/eval.go
index 6b81c760bc..dd948d72a1 100644
--- a/vendor/github.com/hashicorp/hil/eval.go
+++ b/vendor/github.com/hashicorp/hil/eval.go
@@ -41,7 +41,8 @@ func Eval(root ast.Node, config *EvalConfig) (interface{}, ast.Type, error) {
 			ast.TypeString: "__builtin_IntToString",
 		},
 		ast.TypeString: {
-			ast.TypeInt: "__builtin_StringToInt",
+			ast.TypeInt:   "__builtin_StringToInt",
+			ast.TypeFloat: "__builtin_StringToFloat",
 		},
 	}