diff --git a/icu4c/source/common/ucharstrie.cpp b/icu4c/source/common/ucharstrie.cpp
index 4c48323c9176..0e6e0852e9c2 100644
--- a/icu4c/source/common/ucharstrie.cpp
+++ b/icu4c/source/common/ucharstrie.cpp
@@ -177,7 +177,7 @@ UCharsTrie::next(int32_t uchar) {
 UStringTrieResult
 UCharsTrie::next(ConstChar16Ptr ptr, int32_t sLength) {
     const char16_t *s=ptr;
-    if(sLength<0 ? *s==0 : sLength==0) {
+    if(s==nullptr || (sLength<0 ? *s==0 : sLength==0)) {
         // Empty input.
         return current();
     }