diff --git a/src/net.cpp b/src/net.cpp
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -3075,13 +3075,15 @@
 
     // sanitize comments per BIP-0014, format user agent and check total size
     for (const std::string &cmt : gArgs.GetArgs("-uacomment")) {
-        if (cmt != SanitizeString(cmt, SAFE_CHARS_UA_COMMENT)) {
+        const std::string sanitized =
+            SanitizeString(cmt, SAFE_CHARS_UA_COMMENT);
+        if (cmt != sanitized) {
             LogPrintf(
                 "User Agent comment (%s) contains unsafe characters. "
                 "We are going to use a sanitize version of the comment.\n",
                 cmt);
         }
-        uacomments.push_back(cmt);
+        uacomments.push_back(sanitized);
     }
 
     std::string subversion =
diff --git a/src/test/net_tests.cpp b/src/test/net_tests.cpp
--- a/src/test/net_tests.cpp
+++ b/src/test/net_tests.cpp
@@ -59,6 +59,18 @@
     }
 };
 
+class DummyConfigNetTest : public DummyConfig {
+public:
+    bool SetMaxBlockSize(uint64_t maxBlockSize) override {
+        nMaxBlockSize = maxBlockSize;
+        return true;
+    }
+    uint64_t GetMaxBlockSize() const override { return nMaxBlockSize; }
+
+private:
+    uint64_t nMaxBlockSize;
+};
+
 CDataStream AddrmanToStream(CAddrManSerializationMock &_addrman) {
     CDataStream ssPeersIn(SER_DISK, CLIENT_VERSION);
     ssPeersIn << FLATDATA(Params().DiskMagic());
@@ -185,7 +197,7 @@
 }
 
 BOOST_AUTO_TEST_CASE(test_userAgentLength) {
-    GlobalConfig config;
+    DummyConfigNetTest config;
 
     config.SetMaxBlockSize(8000000);
     std::string long_uacomment = "very very very very very very very very very "
@@ -211,4 +223,28 @@
     BOOST_CHECK_EQUAL(userAgent(config), versionMessage.str());
 }
 
+BOOST_AUTO_TEST_CASE(test_userAgentSanitize) {
+    DummyConfigNetTest config;
+
+    config.SetMaxBlockSize(32000000);
+
+    gArgs.ClearMultiArg("-uacomment");
+    const std::string goodua = "A valid user agent comment .,;-_?@";
+    gArgs.ForceSetMultiArg("-uacomment", goodua);
+    std::ostringstream goodSubversion;
+    goodSubversion << "/Bitcoin ABC:" << CLIENT_VERSION_MAJOR << "."
+                   << CLIENT_VERSION_MINOR << "." << CLIENT_VERSION_REVISION
+                   << "(EB32.0; " << goodua << ")/";
+    BOOST_CHECK_EQUAL(userAgent(config), goodSubversion.str());
+
+    gArgs.ClearMultiArg("-uacomment");
+    const std::string badua = "A bad user agent comment /:()+!";
+    gArgs.ForceSetMultiArg("-uacomment", badua);
+    std::ostringstream sanSubversion;
+    sanSubversion << "/Bitcoin ABC:" << CLIENT_VERSION_MAJOR << "."
+                  << CLIENT_VERSION_MINOR << "." << CLIENT_VERSION_REVISION
+                  << "(EB32.0; A bad user agent comment )/";
+    BOOST_CHECK_EQUAL(userAgent(config), sanSubversion.str());
+}
+
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/util.h b/src/util.h
--- a/src/util.h
+++ b/src/util.h
@@ -195,6 +195,9 @@
     // Remove an arg setting, used only in testing
     void ClearArg(const std::string &strArg);
 
+    // Remove a multi arg setting, used only in testing
+    void ClearMultiArg(const std::string &strArg);
+
 private:
     // Munge -nofoo into -foo=0 and track the value as negated.
     void InterpretNegatedOption(std::string &key, std::string &val);
diff --git a/src/util.cpp b/src/util.cpp
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -325,6 +325,12 @@
     mapArgs.erase(strArg);
 }
 
+void ArgsManager::ClearMultiArg(const std::string &strArg) {
+    LOCK(cs_args);
+    mapMultiArgs.erase(strArg);
+    mapArgs.erase(strArg);
+}
+
 bool HelpRequested(const ArgsManager &args) {
     return args.IsArgSet("-?") || args.IsArgSet("-h") || args.IsArgSet("-help");
 }