diff --git a/src/ir.cpp b/src/ir.cpp
index a862ff1068fc..4db12f9ce9b8 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -15118,6 +15118,11 @@ static IrInstruction *ir_analyze_bin_op_cmp(IrAnalyze *ira, IrInstructionBinOp *
         ir_add_error_node(ira, source_node, buf_sprintf("comparison of '%s' with null",
             buf_ptr(&non_null_type->name)));
         return ira->codegen->invalid_instruction;
+    } else if (op1->value->type->id == ZigTypeIdUndefined || op2->value->type->id == ZigTypeIdUndefined) {
+        ZigType *other_type = (op1->value->type->id == ZigTypeIdUndefined) ? op2->value->type : op1->value->type;
+        ir_add_error_node(ira, source_node, buf_sprintf("comparison of '%s' with undefined",
+            buf_ptr(&other_type->name)));
+        return ira->codegen->invalid_instruction;
     } else if (is_equality_cmp && (
         (op1->value->type->id == ZigTypeIdEnumLiteral && op2->value->type->id == ZigTypeIdUnion) ||
         (op2->value->type->id == ZigTypeIdEnumLiteral && op1->value->type->id == ZigTypeIdUnion)))
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index 450f91b9be5d..029c35754031 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -2,6 +2,14 @@ const tests = @import("tests.zig");
 const builtin = @import("builtin");
 
 pub fn addCases(cases: *tests.CompileErrorContext) void {
+    cases.add("comparing against undefined",
+        \\pub fn main() void {
+        \\    _ = 2 == undefined;
+        \\}
+    , &[_][]const u8{
+        "tmp.zig:2:11: error: comparison of 'comptime_int' with undefined",
+    });
+
     cases.add("slice sentinel mismatch",
         \\fn foo() [:0]u8 {
         \\    var x: []u8 = undefined;