diff --git a/icu4c/source/i18n/translit.cpp b/icu4c/source/i18n/translit.cpp
index f5e8a56e722..a1f4813083a 100644
--- a/icu4c/source/i18n/translit.cpp
+++ b/icu4c/source/i18n/translit.cpp
@@ -129,7 +129,11 @@ inline UBool positionIsValid(UTransPosition& index, int32_t len) {
 Transliterator::Transliterator(const UnicodeString& theID,
                                UnicodeFilter* adoptedFilter) :
     UObject(), ID(theID), filter(adoptedFilter),
-    maximumContextLength(0) {}
+    maximumContextLength(0) {
+
+    // NUL-terminate the ID string
+    ID.getTerminatedBuffer();
+}
 
 /**
  * Destructor.
@@ -144,6 +148,10 @@ Transliterator::~Transliterator() {
 Transliterator::Transliterator(const Transliterator& other) :
     UObject(other), ID(other.ID), filter(0),
     maximumContextLength(other.maximumContextLength) {
+
+    // NUL-terminate the ID string
+    ID.getTerminatedBuffer();
+
     if (other.filter != 0) {
         // We own the filter, so we must have our own copy
         filter = (UnicodeFilter*) other.filter->clone();
@@ -155,6 +163,9 @@ Transliterator::Transliterator(const Transliterator& other) :
  */
 Transliterator& Transliterator::operator=(const Transliterator& other) {
     ID = other.ID;
+    // NUL-terminate the ID string
+    ID.getTerminatedBuffer();
+
     maximumContextLength = other.maximumContextLength;
     adoptFilter((other.filter == 0) ? 0 : (UnicodeFilter*) other.filter->clone());
     return *this;