diff --git a/src/AstGen.zig b/src/AstGen.zig
index e30f3a272c..019e73c983 100644
--- a/src/AstGen.zig
+++ b/src/AstGen.zig
@@ -5008,6 +5008,7 @@ fn ifExpr(
                 const token_name_str = tree.tokenSlice(token_name_index);
                 if (mem.eql(u8, "_", token_name_str))
                     break :s &then_scope.base;
+                try astgen.detectLocalShadowing(&then_scope.base, ident_name, token_name_index);
                 payload_val_scope = .{
                     .parent = &then_scope.base,
                     .gen_zir = &then_scope,
@@ -5030,6 +5031,7 @@ fn ifExpr(
                 break :s &then_scope.base;
             const payload_inst = try then_scope.addUnNode(tag, cond.inst, node);
             const ident_name = try astgen.identAsString(ident_token);
+            try astgen.detectLocalShadowing(&then_scope.base, ident_name, ident_token);
             payload_val_scope = .{
                 .parent = &then_scope.base,
                 .gen_zir = &then_scope,
@@ -5071,6 +5073,7 @@ fn ifExpr(
                 const error_token_str = tree.tokenSlice(error_token);
                 if (mem.eql(u8, "_", error_token_str))
                     break :s &else_scope.base;
+                try astgen.detectLocalShadowing(&else_scope.base, ident_name, error_token);
                 payload_val_scope = .{
                     .parent = &else_scope.base,
                     .gen_zir = &else_scope,
diff --git a/test/cases.zig b/test/cases.zig
index f5eb566816..f235992f71 100644
--- a/test/cases.zig
+++ b/test/cases.zig
@@ -1108,6 +1108,33 @@ pub fn addCases(ctx: *TestContext) !void {
             ":5:13: error: redeclaration of local variable 'i'",
             ":2:9: note: previous declaration here",
         });
+        case.addError(
+            \\pub fn main() void {
+            \\    var i = 0;
+            \\    if (true) |i| {}
+            \\}
+        , &[_][]const u8{
+            ":3:16: error: redeclaration of local variable 'i'",
+            ":2:9: note: previous declaration here",
+        });
+        case.addError(
+            \\pub fn main() void {
+            \\    var i = 0;
+            \\    if (true) |i| {} else |e| {}
+            \\}
+        , &[_][]const u8{
+            ":3:16: error: redeclaration of local variable 'i'",
+            ":2:9: note: previous declaration here",
+        });
+        case.addError(
+            \\pub fn main() void {
+            \\    var i = 0;
+            \\    if (true) |_| {} else |i| {}
+            \\}
+        , &[_][]const u8{
+            ":3:28: error: redeclaration of local variable 'i'",
+            ":2:9: note: previous declaration here",
+        });
     }
 
     {