diff --git a/src/codegen/c.zig b/src/codegen/c.zig
index 269383884d61728b748e6b566999274dee7a9193..d54ef6b6606cde1e2b00f20237cde1067f64ac7b 100644
--- a/src/codegen/c.zig
+++ b/src/codegen/c.zig
@@ -3193,7 +3193,7 @@ fn airEquality(
 
     try writer.writeAll(" = ");
 
-    if (operand_ty.tag() == .optional) {
+    if (operand_ty.zigTypeTag() == .Optional and !operand_ty.isPtrLikeOptional()) {
         // (A && B)  || (C && (A == B))
         // A = lhs.is_null  ;  B = rhs.is_null  ;  C = rhs.payload == lhs.payload
 
@@ -3984,9 +3984,9 @@ fn airIsNull(
 
     const rhs = if (!payload_ty.hasRuntimeBitsIgnoreComptime())
         TypedValue{ .ty = Type.bool, .val = Value.@"true" }
-    else if (operand_ty.isPtrLikeOptional())
+    else if (optional_ty.isPtrLikeOptional())
         // operand is a regular pointer, test `operand !=/== NULL`
-        TypedValue{ .ty = operand_ty, .val = Value.@"null" }
+        TypedValue{ .ty = optional_ty, .val = Value.@"null" }
     else if (payload_ty.zigTypeTag() == .ErrorSet)
         TypedValue{ .ty = payload_ty, .val = Value.zero }
     else if (payload_ty.isSlice() and optional_ty.optionalReprIsPayload()) rhs: {
diff --git a/test/behavior/bugs/1851.zig b/test/behavior/bugs/1851.zig
index cdbd5e26f7a720aae3251853a95c33898fbbe313..6209a2f2f18b932101000a6ad8f4b8365fa3e08d 100644
--- a/test/behavior/bugs/1851.zig
+++ b/test/behavior/bugs/1851.zig
@@ -5,7 +5,6 @@ const expect = std.testing.expect;
 test "allocation and looping over 3-byte integer" {
     if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
-    if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
 
diff --git a/test/behavior/cast.zig b/test/behavior/cast.zig
index b1f9e86c05b4c684a34c073e0b8ed1d857bed477..573f3a7ac246a234732789168002096a51ca99d3 100644
--- a/test/behavior/cast.zig
+++ b/test/behavior/cast.zig
@@ -1178,7 +1178,6 @@ fn cast128Float(x: u128) f128 {
 
 test "implicit cast from *[N]T to ?[*]T" {
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
-    if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO