diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
--- a/flang/lib/Optimizer/CodeGen/CodeGen.cpp
+++ b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -1064,6 +1064,15 @@
                                         /*isVarArg=*/false));
 }
 
+static unsigned getDimension(mlir::LLVM::LLVMArrayType ty) {
+  unsigned result = 1;
+  for (auto eleTy = ty.getElementType().dyn_cast<mlir::LLVM::LLVMArrayType>();
+       eleTy;
+       eleTy = eleTy.getElementType().dyn_cast<mlir::LLVM::LLVMArrayType>())
+    ++result;
+  return result;
+}
+
 namespace {
 /// Lower a `fir.freemem` instruction into `llvm.call @free`
 struct FreeMemOpConversion : public FIROpConversion<fir::FreeMemOp> {
@@ -1383,9 +1392,15 @@
     llvm::SmallVector<mlir::Value> gepOperands;
     auto baseType =
         base.getType().cast<mlir::LLVM::LLVMPointerType>().getElementType();
-    if (baseType.isa<mlir::LLVM::LLVMArrayType>()) {
+    if (auto arrayType = baseType.dyn_cast<mlir::LLVM::LLVMArrayType>()) {
+      // FIXME: The baseType should be the array element type here, meaning
+      // there should at most be one dimension (constant length characters are
+      // lowered to LLVM as an array of length one characters.). However, using
+      // the character type in the GEP does not lead to correct GEPs when llvm
+      // opaque pointers are enabled.
       auto idxTy = this->lowerTy().indexType();
-      gepOperands.push_back(genConstantIndex(loc, idxTy, rewriter, 0));
+      gepOperands.append(getDimension(arrayType),
+                         genConstantIndex(loc, idxTy, rewriter, 0));
       gepOperands.push_back(lowerBound);
     } else {
       gepOperands.push_back(lowerBound);
@@ -1928,15 +1943,6 @@
   }
 
 private:
-  static unsigned getDimension(mlir::LLVM::LLVMArrayType ty) {
-    unsigned result = 1;
-    for (auto eleTy = ty.getElementType().dyn_cast<mlir::LLVM::LLVMArrayType>();
-         eleTy;
-         eleTy = eleTy.getElementType().dyn_cast<mlir::LLVM::LLVMArrayType>())
-      ++result;
-    return result;
-  }
-
   static mlir::Type getArrayElementType(mlir::LLVM::LLVMArrayType ty) {
     auto eleTy = ty.getElementType();
     while (auto arrTy = eleTy.dyn_cast<mlir::LLVM::LLVMArrayType>())
diff --git a/flang/test/Fir/embox.fir b/flang/test/Fir/embox.fir
--- a/flang/test/Fir/embox.fir
+++ b/flang/test/Fir/embox.fir
@@ -75,7 +75,7 @@
   %1 = fir.slice %c1, %c2, %c1, %c1, %c3, %c1 substr %c1_i64, %c2_i64 : (index, index, index, index, index, index, i64, i64) -> !fir.slice<2>
   %2 = fir.embox %arg0(%0) [%1] : (!fir.ref<!fir.array<2x3x!fir.char<1,4>>>, !fir.shape<2>, !fir.slice<2>) -> !fir.box<!fir.array<?x?x!fir.char<1,?>>>
   // CHECK: %[[addr:.*]] = getelementptr [3 x [2 x [4 x i8]]], ptr %[[arg0]], i64 0, i64 0, i64 0
-  // CHECK: %[[substringAddr:.*]] = getelementptr {{.*}}, ptr %[[addr]], i64 0, i64 1
+  // CHECK: %[[substringAddr:.*]] = getelementptr {{.*}}, ptr %[[addr]], i64 0, i64 0, i64 0, i64 1
   // CHECK: insertvalue {[[descriptorType:.*]]} { ptr undef, i64 2, i32 20180515, i8 2, i8 40, i8 0, i8 0,
   // CHECK-SAME: [2 x [3 x i64]] [{{\[}}3 x i64] [i64 1, i64 2, i64 4], [3 x i64] [i64 1, i64 3, i64 8]] },
   // CHECK-SAME: ptr %[[substringAddr]], 0