diff --git a/flang-rt/lib/runtime/execute.cpp b/flang-rt/lib/runtime/execute.cpp
index b843a0c7f463..4fd6a1e06021 100644
--- a/flang-rt/lib/runtime/execute.cpp
+++ b/flang-rt/lib/runtime/execute.cpp
@@ -48,19 +48,15 @@ enum CMD_STAT {
   SIGNAL_ERR = 7
 };
 
-// Override CopyCharsToDescriptor in tools.h, pass string directly
-void CopyCharsToDescriptor(const Descriptor &value, const char *rawValue) {
-  CopyCharsToDescriptor(value, rawValue, std::strlen(rawValue));
-}
-
-void CheckAndCopyCharsToDescriptor(
+static void CheckAndCopyCharsToDescriptor(
     const Descriptor *value, const char *rawValue) {
   if (value) {
-    CopyCharsToDescriptor(*value, rawValue);
+    CopyAndPad(value->OffsetElement(), rawValue, value->ElementBytes(),
+        std::strlen(rawValue));
   }
 }
 
-void CheckAndStoreIntToDescriptor(
+static void CheckAndStoreIntToDescriptor(
     const Descriptor *intVal, std::int64_t value, Terminator &terminator) {
   if (intVal) {
     StoreIntToDescriptor(intVal, value, terminator);
diff --git a/flang-rt/unittests/Runtime/CommandTest.cpp b/flang-rt/unittests/Runtime/CommandTest.cpp
index 3bed8acafc59..ed640d426adc 100644
--- a/flang-rt/unittests/Runtime/CommandTest.cpp
+++ b/flang-rt/unittests/Runtime/CommandTest.cpp
@@ -360,18 +360,23 @@ TEST_F(ZeroArguments, ECLNotExecutedCommandErrorSync) {
   bool wait{true};
   OwningPtr<Descriptor> exitStat{IntDescriptor(404)};
   OwningPtr<Descriptor> cmdStat{IntDescriptor(202)};
-  OwningPtr<Descriptor> cmdMsg{CharDescriptor("cmd msg buffer XXXXXXXX")};
+  // Use longer character string to check padding
+  OwningPtr<Descriptor> cmdMsg{CharDescriptor(
+      "Command cannot be executed with exit code: XXXXXXXXXXX.")};
 
   RTNAME(ExecuteCommandLine)
   (*command.get(), wait, exitStat.get(), cmdStat.get(), cmdMsg.get());
 #ifdef _WIN32
   CheckDescriptorEqInt<std::int64_t>(exitStat.get(), 9009);
   CheckDescriptorEqInt<std::int64_t>(cmdStat.get(), 5);
-  CheckDescriptorEqStr(cmdMsg.get(), "Command not found.");
+  CheckDescriptorEqStr(
+      cmdMsg.get(), GetPaddedStr("Command not found.", cmdMsg->ElementBytes()));
 #else
   CheckDescriptorEqInt<std::int64_t>(exitStat.get(), 126);
   CheckDescriptorEqInt<std::int64_t>(cmdStat.get(), 4);
-  CheckDescriptorEqStr(cmdMsg.get(), "Command cannot be execu");
+  CheckDescriptorEqStr(cmdMsg.get(),
+      GetPaddedStr("Command cannot be executed with exit code: 126.",
+          cmdMsg->ElementBytes()));
   // removing the file only on Linux (file is not created on Win)
   OwningPtr<Descriptor> commandClean{
       CharDescriptor("rm -f NotExecutedCommandFile")};
@@ -396,11 +401,13 @@ TEST_F(ZeroArguments, ECLNotFoundCommandErrorSync) {
 #ifdef _WIN32
   CheckDescriptorEqInt<std::int64_t>(exitStat.get(), 9009);
   CheckDescriptorEqInt<std::int64_t>(cmdStat.get(), 5);
-  CheckDescriptorEqStr(cmdMsg.get(), "Command not found.");
+  CheckDescriptorEqStr(
+      cmdMsg.get(), GetPaddedStr("Command not found.", cmdMsg->ElementBytes()));
 #else
   CheckDescriptorEqInt<std::int64_t>(exitStat.get(), 127);
   CheckDescriptorEqInt<std::int64_t>(cmdStat.get(), 5);
-  CheckDescriptorEqStr(cmdMsg.get(), "Command not found with exit");
+  CheckDescriptorEqStr(cmdMsg.get(),
+      GetPaddedStr("Command not found with exit", cmdMsg->ElementBytes()));
 #endif
 }