diff --git a/icu4c/source/common/rbbi.cpp b/icu4c/source/common/rbbi.cpp
index cd05c346e0a..7fa3768ef66 100644
--- a/icu4c/source/common/rbbi.cpp
+++ b/icu4c/source/common/rbbi.cpp
@@ -569,9 +569,12 @@ int32_t RuleBasedBreakIterator::preceding(int32_t offset) {
         // move backwards one codepoint to prepare for moving forwards to a
         // safe point.
         // this handles offset being between a supplementary character
+        // TODO:  would it be better to just check for being in the middle of a surrogate pair,
+        //        rather than adjusting the position unconditionally?
+        //        (Change would interact with safe rules.)
         fText->previous32();
         handleNext(fData->fSafeFwdTable);
-        int32_t result = /*previous(); */ fText->getIndex();
+        int32_t result = fText->getIndex();
         while (result >= offset) {
             result = previous();
         }
diff --git a/icu4c/source/data/brkitr/line.txt b/icu4c/source/data/brkitr/line.txt
index 0a53aa193aa..e3abf99ff10 100644
--- a/icu4c/source/data/brkitr/line.txt
+++ b/icu4c/source/data/brkitr/line.txt
@@ -388,6 +388,4 @@ $QU $CM* $SP+;
 $CL $CM* $SP+;
 
 # LB 18
-$HY $CM* $NU;
-$IS $CM* $CL;
-$SY $CM* $CL;
+$CM* $PRcm? ($OPcm | $HYcm)? $NU;