diff --git a/flang/include/flang/Optimizer/Dialect/FIROps.td b/flang/include/flang/Optimizer/Dialect/FIROps.td
index 1699d7890fb04..481aeefb0ab2e 100644
--- a/flang/include/flang/Optimizer/Dialect/FIROps.td
+++ b/flang/include/flang/Optimizer/Dialect/FIROps.td
@@ -1907,21 +1907,38 @@ def fir_SliceOp : fir_Op<"slice", [NoSideEffect, AttrSizedOperandSegments]> {
 
     ```mlir
       %fld = fir.field_index component, !fir.type<t{...component:ct...}>
-      %d = fir.slice %lo, %hi, %step path %fld : (index, index, index, !fir.field) -> !fir.slice<1>
+      %d = fir.slice %lo, %hi, %step path %fld :
+          (index, index, index, !fir.field) -> !fir.slice<1>
+    ```
+
+    Projections of `!fir.char` type can be further narrowed to invariant
+    substrings.
+
+    ```mlir
+      %d = fir.slice %lo, %hi, %step substr %offset, %width :
+          (index, index, index, index, index) -> !fir.slice<1>
     ```
   }];
 
   let arguments = (ins
-    Variadic<AnyCoordinateType>:$triples,
-    Variadic<AnyComponentType>:$fields
+    Variadic<AnyIntegerType>:$triples,
+    Variadic<AnyComponentType>:$fields,
+    Variadic<AnyIntegerType>:$substr
   );
 
   let results = (outs fir_SliceType);
 
   let assemblyFormat = [{
-    $triples (`path` $fields^)? attr-dict `:` functional-type(operands, results)
+    $triples (`path` $fields^)? (`substr` $substr^)? attr-dict `:`
+      functional-type(operands, results)
   }];
 
+  let builders = [
+    OpBuilder<(ins "mlir::ValueRange":$triples,
+      CArg<"mlir::ValueRange", "llvm::None">:$fields,
+      CArg<"mlir::ValueRange", "llvm::None">:$substr)>
+  ];
+
   let verifier = "return ::verify(*this);";
 
   let extraClassDeclaration = [{
diff --git a/flang/lib/Optimizer/Dialect/FIROps.cpp b/flang/lib/Optimizer/Dialect/FIROps.cpp
index 64174b8892dfc..ee9cb5372c58b 100644
--- a/flang/lib/Optimizer/Dialect/FIROps.cpp
+++ b/flang/lib/Optimizer/Dialect/FIROps.cpp
@@ -2811,13 +2811,21 @@ static mlir::LogicalResult verify(fir::ShiftOp &op) {
 // SliceOp
 //===----------------------------------------------------------------------===//
 
+void fir::SliceOp::build(mlir::OpBuilder &builder, mlir::OperationState &result,
+                         mlir::ValueRange trips, mlir::ValueRange path,
+                         mlir::ValueRange substr) {
+  const auto rank = trips.size() / 3;
+  auto sliceTy = fir::SliceType::get(builder.getContext(), rank);
+  build(builder, result, sliceTy, trips, path, substr);
+}
+
 /// Return the output rank of a slice op. The output rank must be between 1 and
 /// the rank of the array being sliced (inclusive).
 unsigned fir::SliceOp::getOutputRank(mlir::ValueRange triples) {
   unsigned rank = 0;
   if (!triples.empty()) {
     for (unsigned i = 1, end = triples.size(); i < end; i += 3) {
-      auto op = triples[i].getDefiningOp();
+      auto *op = triples[i].getDefiningOp();
       if (!mlir::isa_and_nonnull<fir::UndefOp>(op))
         ++rank;
     }
diff --git a/flang/test/Fir/fir-ops.fir b/flang/test/Fir/fir-ops.fir
index 2323cbc71ff1a..47805bf83b0a7 100644
--- a/flang/test/Fir/fir-ops.fir
+++ b/flang/test/Fir/fir-ops.fir
@@ -699,3 +699,13 @@ func @char_convert() {
   fir.char_convert %2 for %1 to %3 : !fir.ref<!fir.char<1>>, i32, !fir.ref<!fir.array<?x!fir.char<2,?>>>
   return
 }
+
+func @slice_substr() {
+  %lb = arith.constant 0 : index
+  %ub = arith.constant 42 : index
+  %c1 = arith.constant 1 : index
+  %offset = arith.constant 10 : index
+  %0 = fir.slice %lb, %ub, %c1 substr %offset, %c1 : (index, index, index, index, index) -> !fir.slice<1>
+  // CHECK: fir.slice %{{.*}}, %{{.*}}, %{{.*}} substr %{{.*}}, %{{.*}} : (index, index, index, index, index) -> !fir.slice<1>
+  return
+}
diff --git a/flang/test/Fir/invalid.fir b/flang/test/Fir/invalid.fir
index a43c5614ec860..ca9c3b69bd2f9 100644
--- a/flang/test/Fir/invalid.fir
+++ b/flang/test/Fir/invalid.fir
@@ -606,3 +606,13 @@ func @bad_array_modify(%arr1 : !fir.ref<!fir.array<?x?xf32>>, %m : index, %n : i
   fir.array_merge_store %av1, %av2 to %arr1 : !fir.array<?x?xf32>, !fir.array<?x?xf32>, !fir.ref<!fir.array<?x?xf32>>
   return
 }
+
+// -----
+
+func @slice_must_be_integral() {
+  %0 = arith.constant 42 : i32
+  %1 = fir.field_index field, !fir.type<t(param:i32){field:i32}> (%0 : i32)
+  // expected-error@+1 {{'fir.slice' op operand #0 must be any integer, but got '!fir.field'}}
+  %2 = fir.slice %1, %1, %1 : (!fir.field, !fir.field, !fir.field) -> !fir.slice<1>
+  return
+}