diff --git a/grammar.js b/grammar.js
index 96f12b7b7..f8acc0b6d 100644
--- a/grammar.js
+++ b/grammar.js
@@ -455,7 +455,15 @@ module.exports = grammar({
         binaryExpr(prec.left, 4, ">", $._case_clause_guard_expression),
         binaryExpr(prec.left, 4, ">=", $._case_clause_guard_expression),
         binaryExpr(prec.left, 4, ">.", $._case_clause_guard_expression),
-        binaryExpr(prec.left, 4, ">=.", $._case_clause_guard_expression)
+        binaryExpr(prec.left, 4, ">=.", $._case_clause_guard_expression),
+        binaryExpr(prec.left, 5, "+", $._case_clause_guard_expression),
+        binaryExpr(prec.left, 5, "+.", $._case_clause_guard_expression),
+        binaryExpr(prec.left, 5, "-", $._case_clause_guard_expression),
+        binaryExpr(prec.left, 5, "-.", $._case_clause_guard_expression),
+        binaryExpr(prec.left, 6, "*", $._case_clause_guard_expression),
+        binaryExpr(prec.left, 6, "*.", $._case_clause_guard_expression),
+        binaryExpr(prec.left, 6, "/", $._case_clause_guard_expression),
+        binaryExpr(prec.left, 6, "/.", $._case_clause_guard_expression)
       ),
     _case_clause_guard_unit: ($) =>
       choice(
diff --git a/test/corpus/guard_expressions.txt b/test/corpus/guard_expressions.txt
new file mode 100644
index 000000000..17fad1e69
--- /dev/null
+++ b/test/corpus/guard_expressions.txt
@@ -0,0 +1,73 @@
+================================================================================
+Guard Expressions
+================================================================================
+
+case value {
+  n if n + 1 > 10 -> True
+  n if n / 2 < 5 -> False
+}
+
+case value {
+  n if n -. 1.0 <. 10.0 -> True
+  n if n *. 2 >. 5 -> False
+}
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (case
+    (case_subjects
+      (identifier))
+    (case_clauses
+      (case_clause
+        (case_clause_patterns
+          (case_clause_pattern
+            (identifier)))
+        (case_clause_guard
+          (binary_expression
+            (binary_expression
+              (identifier)
+              (integer))
+            (integer)))
+        (record
+          (constructor_name)))
+      (case_clause
+        (case_clause_patterns
+          (case_clause_pattern
+            (identifier)))
+        (case_clause_guard
+          (binary_expression
+            (binary_expression
+              (identifier)
+              (integer))
+            (integer)))
+        (record
+          (constructor_name)))))
+  (case
+    (case_subjects
+      (identifier))
+    (case_clauses
+      (case_clause
+        (case_clause_patterns
+          (case_clause_pattern
+            (identifier)))
+        (case_clause_guard
+          (binary_expression
+            (binary_expression
+              (identifier)
+              (float))
+            (float)))
+        (record
+          (constructor_name)))
+      (case_clause
+        (case_clause_patterns
+          (case_clause_pattern
+            (identifier)))
+        (case_clause_guard
+          (binary_expression
+            (binary_expression
+              (identifier)
+              (integer))
+            (integer)))
+        (record
+          (constructor_name))))))