diff --git a/icu4c/source/common/ucnv_ct.cpp b/icu4c/source/common/ucnv_ct.cpp
index e363193860a..51e31aa4116 100644
--- a/icu4c/source/common/ucnv_ct.cpp
+++ b/icu4c/source/common/ucnv_ct.cpp
@@ -315,6 +315,7 @@ _CompoundTextClose(UConverter *converter) {
         }
 
         uprv_free(converter->extraInfo);
+        converter->extraInfo = NULL;
     }
 }