diff --git a/core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java b/core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java
index 964fa03f8f91..979ed20cb111 100644
--- a/core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java
+++ b/core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java
@@ -35,8 +35,6 @@
 import org.apache.calcite.sql.SqlLiteral;
 import org.apache.calcite.sql.SqlNode;
 import org.apache.calcite.sql.SqlNodeList;
-import org.apache.calcite.sql.SqlOperator;
-import org.apache.calcite.sql.SqlSyntax;
 import org.apache.calcite.sql.SqlUtil;
 import org.apache.calcite.sql.SqlWriter;
 import org.apache.calcite.sql.fun.SqlLibraryOperators;
@@ -49,6 +47,7 @@
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import static org.apache.calcite.util.RelToSqlConverterUtil.unparseBoolLiteralToCondition;
+import static org.apache.calcite.util.RelToSqlConverterUtil.unparseWithBinaryOperator;
 
 import static java.util.Objects.requireNonNull;
 
@@ -222,8 +221,8 @@ private static SqlNode createDatetimeCastSpec(String typeAlias, RelDataType type
         unparseFloor(writer, call);
         break;
       case MOD:
-        SqlOperator op = SqlStdOperatorTable.PERCENT_REMAINDER;
-        SqlSyntax.BINARY.unparse(writer, op, call, leftPrec, rightPrec);
+        unparseWithBinaryOperator(writer, SqlStdOperatorTable.PERCENT_REMAINDER, call,
+            leftPrec, rightPrec);
         break;
       case SAFE_CAST:
         // MSSQL uses TRY_CAST instead of SAFE_CAST (BigQuery)
diff --git a/core/src/main/java/org/apache/calcite/util/RelToSqlConverterUtil.java b/core/src/main/java/org/apache/calcite/util/RelToSqlConverterUtil.java
index db417179afc3..9041dbecd163 100644
--- a/core/src/main/java/org/apache/calcite/util/RelToSqlConverterUtil.java
+++ b/core/src/main/java/org/apache/calcite/util/RelToSqlConverterUtil.java
@@ -31,7 +31,9 @@
 import org.apache.calcite.sql.SqlLiteral;
 import org.apache.calcite.sql.SqlMapTypeNameSpec;
 import org.apache.calcite.sql.SqlNode;
+import org.apache.calcite.sql.SqlOperator;
 import org.apache.calcite.sql.SqlSpecialOperator;
+import org.apache.calcite.sql.SqlSyntax;
 import org.apache.calcite.sql.SqlTypeNameSpec;
 import org.apache.calcite.sql.SqlWriter;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
@@ -339,6 +341,26 @@ public static void unparseBoolLiteralToCondition(SqlWriter writer, boolean value
     writer.endList(frame);
   }
 
+  /**
+   * Writes a two-operand call with an operator other than its own,
+   * parenthesized as that operator requires.
+   *
+   * <p>{@link SqlCall#unparse} chooses the parentheses from the call's own
+   * operator before the dialect is consulted, so an operator that binds less
+   * tightly needs them added here.
+   */
+  public static void unparseWithBinaryOperator(SqlWriter writer, SqlOperator operator,
+      SqlCall call, int leftPrec, int rightPrec) {
+    if (leftPrec > operator.getLeftPrec()
+        || (operator.getRightPrec() <= rightPrec && rightPrec != 0)) {
+      final SqlWriter.Frame frame = writer.startList("(", ")");
+      SqlSyntax.BINARY.unparse(writer, operator, call, 0, 0);
+      writer.endList(frame);
+    } else {
+      SqlSyntax.BINARY.unparse(writer, operator, call, leftPrec, rightPrec);
+    }
+  }
+
   /**
    * Transformation Map type from {@code MAP<VARCHAR,VARCHAR>} to {@code Map(VARCHAR,VARCHAR)}.
    */
diff --git a/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java b/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
index 877a1e99ee62..22046bd8a799 100644
--- a/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
+++ b/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
@@ -11820,6 +11820,22 @@ private void checkLiteral2(String expression, String expected) {
     sql(query).dialect(MssqlSqlDialect.DEFAULT).ok(mssqlExpected);
   }
 
+  /** Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-7778">[CALCITE-7778]
+   * JDBC adapter for MSSQL generates % for MOD without preserving grouping,
+   * giving wrong results</a>. */
+  @Test void testModFunctionGroupingForMSSQL() {
+    final String from = "\nFROM (VALUES (0)) AS [t] ([ZERO])";
+    sql("select 100 / mod(11, 3)").dialect(MssqlSqlDialect.DEFAULT)
+        .ok("SELECT 100 / (11 % 3)" + from);
+    sql("select 100 * mod(11, 3)").dialect(MssqlSqlDialect.DEFAULT)
+        .ok("SELECT 100 * (11 % 3)" + from);
+    sql("select mod(100, mod(11, 3))").dialect(MssqlSqlDialect.DEFAULT)
+        .ok("SELECT 100 % (11 % 3)" + from);
+    // % already binds more tightly than -, so no parentheses are needed
+    sql("select 100 - mod(11, 3)").dialect(MssqlSqlDialect.DEFAULT)
+        .ok("SELECT 100 - 11 % 3" + from);
+  }
 
   /** Test case for
    * <a href="https://issues.apache.org/jira/browse/CALCITE-6655">[CALCITE-6655]