diff --git a/src/check_stmt.cpp b/src/check_stmt.cpp
index 2b547a30a..2502ab352 100644
--- a/src/check_stmt.cpp
+++ b/src/check_stmt.cpp
@@ -1167,6 +1167,8 @@ gb_internal void check_switch_stmt(CheckerContext *ctx, Ast *node, u32 mod_flags
 	ast_node(ss, SwitchStmt, node);
 
 	Operand x = {};
+	// Tagless switch cases are independent predicates, not case values.
+	bool check_duplicate_cases = ss->tag != nullptr;
 
 	mod_flags |= Stmt_BreakAllowed | Stmt_FallthroughAllowed;
 	check_open_scope(ctx, node);
@@ -1292,7 +1294,9 @@ gb_internal void check_switch_stmt(CheckerContext *ctx, Ast *node, u32 mod_flags
 				Operand b1 = rhs;
 				check_comparison(ctx, expr, &a1, &b1, Token_LtEq);
 
-				add_to_seen_map(ctx, &seen, upper_op, x, lhs, rhs);
+				if (check_duplicate_cases) {
+					add_to_seen_map(ctx, &seen, upper_op, x, lhs, rhs);
+				}
 
 				if (is_type_string16(x.type)) {
 					// NOTE(bill): Force dependency for strings here
@@ -1325,7 +1329,9 @@ gb_internal void check_switch_stmt(CheckerContext *ctx, Ast *node, u32 mod_flags
 					}
 					t = default_type(t);
 					add_type_info_type(ctx, t);
-					add_type_to_seen_map(ctx, &seen, y);
+					if (check_duplicate_cases) {
+						add_type_to_seen_map(ctx, &seen, y);
+					}
 				} else {
 					convert_to_typed(ctx, &y, x.type);
 					if (y.mode == Addressing_Invalid) {
@@ -1342,7 +1348,9 @@ gb_internal void check_switch_stmt(CheckerContext *ctx, Ast *node, u32 mod_flags
 						continue;
 					}
 					update_untyped_expr_type(ctx, z.expr, x.type, !is_type_untyped(x.type));
-					add_to_seen_map(ctx, &seen, y);
+					if (check_duplicate_cases) {
+						add_to_seen_map(ctx, &seen, y);
+					}
 				}
 			}
 		}
diff --git a/tests/issues/run.bat b/tests/issues/run.bat
index 1beb880d9..6fdf22bec 100644
--- a/tests/issues/run.bat
+++ b/tests/issues/run.bat
@@ -52,6 +52,8 @@ set COMMON=-define:ODIN_TEST_FANCY=false -file -vet -strict-style -ignore-unused
 ..\..\..\odin check ..\test_issue_foreign_redeclaration_mismatch.odin -no-entry-point %COMMON% 2>&1 | find /c "Error:" | findstr /x "1" || exit /b
 ..\..\..\odin doc ..\test_issue_asm_doc_category.odin -file 2>&1 | find /c "asm templates" | findstr /x "1" || exit /b
 ..\..\..\odin build ..\test_issue_7037.odin %COMMON% -o:none  || exit /b
+..\..\..\odin test ..\test_issue_7421.odin %COMMON% || exit /b
+..\..\..\odin check ..\test_issue_7421_tagged_duplicate.odin %COMMON% 2>&1 | find /c "Error: Duplicate case" | findstr /x "1" || exit /b
 ..\..\..\odin build ..\test_issue_7188.odin %COMMON%  || exit /b
 clang -c ..\test_issue_sysv_abi.c -o test_issue_sysv_abi_c.o || exit /b
 ..\..\..\odin test ..\test_issue_sysv_abi.odin %COMMON%  || exit /b
diff --git a/tests/issues/run.sh b/tests/issues/run.sh
index 41a0835b4..4f31e69e0 100755
--- a/tests/issues/run.sh
+++ b/tests/issues/run.sh
@@ -91,6 +91,13 @@ $ODIN check ../test_issue_6979.odin -no-entry-point $COMMON_CHECK
 $ODIN test ../test_issue_7008.odin $COMMON
 $ODIN check ../test_issue_7012.odin -no-entry-point $COMMON_CHECK
 $ODIN build ../test_issue_7037.odin $COMMON -o:none
+$ODIN test ../test_issue_7421.odin $COMMON
+if [[ $($ODIN check ../test_issue_7421_tagged_duplicate.odin $COMMON_CHECK 2>&1 >/dev/null | grep -c "Error: Duplicate case") -eq 1 ]]; then
+	echo "SUCCESSFUL 1/1"
+else
+	echo "SUCCESSFUL 0/1"
+	exit 1
+fi
 $ODIN check ../test_issue_7429.odin $COMMON_CHECK
 $ODIN test ../test_issue_7356.odin $COMMON
 $ODIN test ../test_issue_7336.odin $COMMON
diff --git a/tests/issues/test_issue_7421.odin b/tests/issues/test_issue_7421.odin
new file mode 100644
index 000000000..f1a8c5211
--- /dev/null
+++ b/tests/issues/test_issue_7421.odin
@@ -0,0 +1,25 @@
+// Tests issue #7421: constant conditions in a tagless switch are conditions,
+// not values to compare against one another for duplicate cases.
+// https://github.com/odin-lang/Odin/issues/7421
+package test_issues
+
+import "core:testing"
+
+Issue_7421_Alias :: u16
+
+@(test)
+test_issue_7421_tagless_switch_constant_conditions :: proc(t: ^testing.T) {
+	selected := 0
+	switch {
+	case Issue_7421_Alias == u16:
+		selected = 1
+	case Issue_7421_Alias == i32:
+		selected = 2
+	case Issue_7421_Alias == string:
+		selected = 3
+	case:
+		selected = 4
+	}
+
+	testing.expect_value(t, selected, 1)
+}
diff --git a/tests/issues/test_issue_7421_tagged_duplicate.odin b/tests/issues/test_issue_7421_tagged_duplicate.odin
new file mode 100644
index 000000000..e441498da
--- /dev/null
+++ b/tests/issues/test_issue_7421_tagged_duplicate.odin
@@ -0,0 +1,10 @@
+// Regression guard for issue #7421: tagged switches still reject duplicate cases.
+package test_issues
+
+main :: proc() {
+	value := false
+	switch value {
+	case false:
+	case false:
+	}
+}