diff --git a/lib/xmlparse.c b/lib/xmlparse.c
--- a/lib/xmlparse.c
+++ b/lib/xmlparse.c
@@ -453,7 +453,9 @@
 typedef struct accounting {
   XmlBigCount countBytesDirect;
   XmlBigCount countBytesIndirect;
+#ifndef MOZILLA_CLIENT /* don't report debug information */
   unsigned long debugLevel;
+#endif
   float maximumAmplificationFactor; // >=1.0
   unsigned long long activationThresholdBytes;
 } ACCOUNTING;
@@ -466,12 +468,14 @@
   XmlBigCount activationThresholdBytes;
 } MALLOC_TRACKER;

+#ifndef MOZILLA_CLIENT /* don't report debug information */
 typedef struct entity_stats {
   unsigned int countEverOpened;
   unsigned int currentDepth;
   unsigned int maximumDepthSeen;
   unsigned long debugLevel;
 } ENTITY_STATS;
+#endif /* MOZILLA_CLIENT */
 #endif /* XML_GE == 1 */

 typedef enum XML_Error PTRCALL Processor(XML_Parser parser, const char *start,
@@ -630,18 +634,22 @@
 static float accountingGetCurrentAmplification(XML_Parser rootParser);
 static void accountingReportStats(XML_Parser originParser, const char *epilog);
 static void accountingOnAbort(XML_Parser originParser);
+#ifndef MOZILLA_CLIENT /* don't report debug information */
 static void accountingReportDiff(XML_Parser rootParser,
                                  unsigned int levelsAwayFromRootParser,
                                  const char *before, const char *after,
                                  ptrdiff_t bytesMore, int source_line,
                                  enum XML_Account account);
+#endif
 static XML_Bool accountingDiffTolerated(XML_Parser originParser, int tok,
                                         const char *before, const char *after,
                                         int source_line,
                                         enum XML_Account account);

+#ifndef MOZILLA_CLIENT /* don't report debug information */
 static void entityTrackingReportStats(XML_Parser parser, ENTITY *entity,
                                       const char *action, int sourceLine);
+#endif
 static void entityTrackingOnOpen(XML_Parser parser, ENTITY *entity,
                                  int sourceLine);
 static void entityTrackingOnClose(XML_Parser parser, ENTITY *entity,
@@ -651,8 +659,10 @@
 static XML_Parser getRootParserOf(XML_Parser parser,
                                   unsigned int *outLevelDiff);

+#ifndef MOZILLA_CLIENT /* don't report debug information */
 static unsigned long getDebugLevel(const char *variableName,
                                    unsigned long defaultDebugLevel);
+#endif

 #define poolStart(pool) ((pool)->start)
 #define poolLength(pool) ((pool)->ptr - (pool)->start)
@@ -793,8 +803,10 @@
 #if XML_GE == 1
   ACCOUNTING m_accounting;
   MALLOC_TRACKER m_alloc_tracker;
+#ifndef MOZILLA_CLIENT /* don't report debug information */
   ENTITY_STATS m_entity_stats;
-#endif
+#endif /* MOZILLA_CLIENT */
+#endif /* XML_GE == 1 */
 #ifdef MOZILLA_CLIENT /* Report opening tag of mismatched closing tag */
   const XML_Char* m_mismatch;
 #endif
@@ -1209,10 +1221,12 @@

 static unsigned long
 ENTROPY_DEBUG(const char *label, unsigned long entropy) {
+#ifndef MOZILLA_CLIENT /* don't report debug information */
   if (getDebugLevel("EXPAT_ENTROPY_DEBUG", 0) >= 1u) {
     fprintf(stderr, "expat: Entropy: %s --> 0x%0*lx (%lu bytes)\n", label,
             (int)sizeof(entropy) * 2, entropy, (unsigned long)sizeof(entropy));
   }
+#endif
   return entropy;
 }

@@ -1632,15 +1646,19 @@

 #if XML_GE == 1
   memset(&parser->m_accounting, 0, sizeof(ACCOUNTING));
+#ifndef MOZILLA_CLIENT /* don't report debug information */
   parser->m_accounting.debugLevel = getDebugLevel("EXPAT_ACCOUNTING_DEBUG", 0u);
+#endif
   parser->m_accounting.maximumAmplificationFactor
       = EXPAT_BILLION_LAUGHS_ATTACK_PROTECTION_MAXIMUM_AMPLIFICATION_DEFAULT;
   parser->m_accounting.activationThresholdBytes
       = EXPAT_BILLION_LAUGHS_ATTACK_PROTECTION_ACTIVATION_THRESHOLD_DEFAULT;

+#ifndef MOZILLA_CLIENT /* don't report debug information */
   memset(&parser->m_entity_stats, 0, sizeof(ENTITY_STATS));
   parser->m_entity_stats.debugLevel = getDebugLevel("EXPAT_ENTITY_DEBUG", 0u);
-#endif
+#endif /* MOZILLA_CLIENT */
+#endif /* XML_GE == 1 */
 }

 /* moves list of bindings to m_freeBindingList */
@@ -8662,6 +8680,7 @@

 static void
 accountingReportStats(XML_Parser originParser, const char *epilog) {
+#ifndef MOZILLA_CLIENT /* don't report debug information */
   const XML_Parser rootParser = getRootParserOf(originParser, NULL);
   assert(! rootParser->m_parentParser);

@@ -8677,6 +8696,7 @@
           (void *)rootParser, rootParser->m_accounting.countBytesDirect,
           rootParser->m_accounting.countBytesIndirect,
           (double)amplificationFactor, epilog);
+#endif
 }

 static void
@@ -8684,6 +8704,7 @@
   accountingReportStats(originParser, " ABORTING\n");
 }

+#ifndef MOZILLA_CLIENT /* don't report debug information */
 static void
 accountingReportDiff(XML_Parser rootParser,
                      unsigned int levelsAwayFromRootParser, const char *before,
@@ -8720,6 +8741,7 @@
   }
   fprintf(stderr, "\"\n");
 }
+#endif /* MOZILLA_CLIENT */

 static XML_Bool
 accountingDiffTolerated(XML_Parser originParser, int tok, const char *before,
@@ -8767,11 +8789,13 @@
         || (amplificationFactor
             <= rootParser->m_accounting.maximumAmplificationFactor);

+#ifndef MOZILLA_CLIENT /* don't report debug information */
   if (rootParser->m_accounting.debugLevel >= 2u) {
     accountingReportStats(rootParser, "");
     accountingReportDiff(rootParser, levelsAwayFromRootParser, before, after,
                          bytesMore, source_line, account);
   }
+#endif

   return tolerated;
 }
@@ -8790,6 +8814,7 @@
   return parser->m_accounting.countBytesIndirect;
 }

+#ifndef MOZILLA_CLIENT /* don't report debug information */
 static void
 entityTrackingReportStats(XML_Parser rootParser, ENTITY *entity,
                           const char *action, int sourceLine) {
@@ -8813,9 +8838,11 @@
       entity->is_param ? "%" : "&", entityName, action, entity->textLen,
       sourceLine);
 }
+#endif /* MOZILLA_CLIENT */

 static void
 entityTrackingOnOpen(XML_Parser originParser, ENTITY *entity, int sourceLine) {
+#ifndef MOZILLA_CLIENT /* don't report debug information */
   const XML_Parser rootParser = getRootParserOf(originParser, NULL);
   assert(! rootParser->m_parentParser);

@@ -8827,15 +8854,18 @@
   }

   entityTrackingReportStats(rootParser, entity, "OPEN ", sourceLine);
+#endif
 }

 static void
 entityTrackingOnClose(XML_Parser originParser, ENTITY *entity, int sourceLine) {
+#ifndef MOZILLA_CLIENT /* don't report debug information */
   const XML_Parser rootParser = getRootParserOf(originParser, NULL);
   assert(! rootParser->m_parentParser);

   entityTrackingReportStats(rootParser, entity, "CLOSE", sourceLine);
   rootParser->m_entity_stats.currentDepth--;
+#endif
 }

 #endif /* XML_GE == 1 */
@@ -8857,6 +8887,7 @@

 #if XML_GE == 1

+#ifndef MOZILLA_CLIENT /* don't report debug information */
 const char *
 unsignedCharToPrintable(unsigned char c) {
   switch (c) {
@@ -9380,9 +9411,11 @@
   assert(0); /* never gets here */
   // LCOV_EXCL_STOP
 }
+#endif /* MOZILLA_CLIENT */

 #endif /* XML_GE == 1 */

+#ifndef MOZILLA_CLIENT /* don't report debug information */
 static unsigned long
 getDebugLevel(const char *variableName, unsigned long defaultDebugLevel) {
   const char *const valueOrNull = getenv(variableName);
@@ -9401,3 +9434,4 @@

   return debugLevel;
 }
+#endif /* MOZILLA_CLIENT */