diff --git a/test/tools/sancov/merge.test b/test/tools/sancov/merge.test
index 1e220ca26f1..4c95d7c0bb5 100644
--- a/test/tools/sancov/merge.test
+++ b/test/tools/sancov/merge.test
@@ -29,34 +29,34 @@ MERGE1-NEXT:   }
 MERGE1-NEXT: }
 
 MERGE2: {
-MERGE2-NEXT:   "covered-points" : ["BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e132b", "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1472", "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e14c2", "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1520", "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1553", "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1586", "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e178c"],
+MERGE2-NEXT:   "covered-points" : ["04e132b", "04e1472", "04e1520", "04e1553", "04e1586", "14e132b", "14e1472", "14e14c2", "14e1520", "14e1553", "14e1586", "14e178c"],
 MERGE2-NEXT:   "point-symbol-info" : {
 MERGE2-NEXT:     "test/tools/sancov/Inputs/foo.cpp" : {
 MERGE2-NEXT:      "foo()" : {
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e178c" : "5:0",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e178c" : "5:0"
+MERGE2-NEXT:         "04e178c" : "5:0",
+MERGE2-NEXT:         "14e178c" : "5:0"
 MERGE2-NEXT:       }
 MERGE2-NEXT:     },
 MERGE2-NEXT:     "test/tools/sancov/Inputs/test.cpp" : {
 MERGE2-NEXT:       "bar(std::string)" : {
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e132b" : "12:0",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e132b" : "12:0"
+MERGE2-NEXT:         "04e132b" : "12:0",
+MERGE2-NEXT:         "14e132b" : "12:0"
 MERGE2-NEXT:       },
 MERGE2-NEXT:       "main" : {
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1472" : "14:0",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e14c2" : "16:9",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1520" : "17:5",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1553" : "17:5",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1586" : "17:5",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1635" : "19:1",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1690" : "17:5",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1472" : "14:0",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e14c2" : "16:9",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1520" : "17:5",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1553" : "17:5",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1586" : "17:5",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1635" : "19:1",
-MERGE2-NEXT:         "BB3CDD5045AED83906F6ADCC1C4DAF7E2596A6B5:4e1690" : "17:5"
+MERGE2-NEXT:         "04e1472" : "14:0",
+MERGE2-NEXT:         "04e14c2" : "16:9",
+MERGE2-NEXT:         "04e1520" : "17:5",
+MERGE2-NEXT:         "04e1553" : "17:5",
+MERGE2-NEXT:         "04e1586" : "17:5",
+MERGE2-NEXT:         "04e1635" : "19:1",
+MERGE2-NEXT:         "04e1690" : "17:5",
+MERGE2-NEXT:         "14e1472" : "14:0",
+MERGE2-NEXT:         "14e14c2" : "16:9",
+MERGE2-NEXT:         "14e1520" : "17:5",
+MERGE2-NEXT:         "14e1553" : "17:5",
+MERGE2-NEXT:         "14e1586" : "17:5",
+MERGE2-NEXT:         "14e1635" : "19:1",
+MERGE2-NEXT:         "14e1690" : "17:5"
 MERGE2-NEXT:       }
 MERGE2-NEXT:     }
 MERGE2-NEXT:   }
diff --git a/tools/sancov/sancov.cc b/tools/sancov/sancov.cc
index 3513d1e6e22..d7ce120c7e2 100644
--- a/tools/sancov/sancov.cc
+++ b/tools/sancov/sancov.cc
@@ -1079,8 +1079,7 @@ merge(const std::vector<std::unique_ptr<SymbolizedCoverage>> &Coverages) {
     std::string Prefix;
     if (Coverages.size() > 1) {
       // prefix is not needed when there's only one file.
-      Prefix =
-          (Coverage.BinaryHash.size() ? Coverage.BinaryHash : utostr(I)) + ":";
+      Prefix = utostr(I);
     }
 
     for (const auto &Id : Coverage.CoveredIds) {