diff --git a/compiler-rt/lib/fuzzer/FuzzerDriver.cpp b/compiler-rt/lib/fuzzer/FuzzerDriver.cpp
--- a/compiler-rt/lib/fuzzer/FuzzerDriver.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerDriver.cpp
@@ -463,7 +463,7 @@
         CurrentFilePath = Flags.exact_artifact_path;
         WriteToFile(U, CurrentFilePath);
       }
-      Printf("CRASH_MIN: failed to minimize beyond %s (%d bytes), exiting\n",
+      Printf("CRASH_MIN: failed to minimize beyond %s (%zu bytes), exiting\n",
              CurrentFilePath.c_str(), U.size());
       break;
     }
@@ -535,7 +535,7 @@
 
 int AnalyzeDictionary(Fuzzer *F, const std::vector<Unit> &Dict,
                       UnitVector &Corpus) {
-  Printf("Started dictionary minimization (up to %d tests)\n",
+  Printf("Started dictionary minimization (up to %zu tests)\n",
          Dict.size() * Corpus.size() * 2);
 
   // Scores and usage count for each dictionary unit.
@@ -779,7 +779,7 @@
   if (!Options.FocusFunction.empty())
     Options.Entropic = false; // FocusFunction overrides entropic scheduling.
   if (Options.Entropic)
-    Printf("INFO: Running with entropic power schedule (0x%X, %d).\n",
+    Printf("INFO: Running with entropic power schedule (0x%zX, %zu).\n",
            Options.EntropicFeatureFrequencyThreshold,
            Options.EntropicNumberOfRarestFeatures);
   struct EntropicOptions Entropic;
@@ -860,7 +860,7 @@
         RunOneTest(F, Path.c_str(), Options.MaxLen);
       auto StopTime = system_clock::now();
       auto MS = duration_cast<milliseconds>(StopTime - StartTime).count();
-      Printf("Executed %s in %zd ms\n", Path.c_str(), (long)MS);
+      Printf("Executed %s in %ld ms\n", Path.c_str(), (long)MS);
     }
     Printf("***\n"
            "*** NOTE: fuzzing was not performed, you have only\n"
diff --git a/compiler-rt/lib/fuzzer/FuzzerLoop.cpp b/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
--- a/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
@@ -301,7 +301,7 @@
     Printf("       and the timeout value is %d (use -timeout=N to change)\n",
            Options.UnitTimeoutSec);
     DumpCurrentUnit("timeout-");
-    Printf("==%lu== ERROR: libFuzzer: timeout after %d seconds\n", GetPid(),
+    Printf("==%lu== ERROR: libFuzzer: timeout after %zu seconds\n", GetPid(),
            Seconds);
     PrintStackTrace();
     Printf("SUMMARY: libFuzzer: timeout\n");
@@ -314,9 +314,8 @@
   if (EF->__sanitizer_acquire_crash_state &&
       !EF->__sanitizer_acquire_crash_state())
     return;
-  Printf(
-      "==%lu== ERROR: libFuzzer: out-of-memory (used: %zdMb; limit: %zdMb)\n",
-      GetPid(), GetPeakRSSMb(), Options.RssLimitMb);
+  Printf("==%lu== ERROR: libFuzzer: out-of-memory (used: %zdMb; limit: %dMb)\n",
+         GetPid(), GetPeakRSSMb(), Options.RssLimitMb);
   Printf("   To change the out-of-memory limit use -rss_limit_mb=<N>\n\n");
   PrintMemoryProfile();
   DumpCurrentUnit("oom-");
@@ -371,7 +370,7 @@
   Printf("stat::number_of_executed_units: %zd\n", TotalNumberOfRuns);
   Printf("stat::average_exec_per_sec:     %zd\n", ExecPerSec);
   Printf("stat::new_units_added:          %zd\n", NumberOfNewUnitsAdded);
-  Printf("stat::slowest_unit_time_sec:    %zd\n", TimeOfLongestUnitInSeconds);
+  Printf("stat::slowest_unit_time_sec:    %ld\n", TimeOfLongestUnitInSeconds);
   Printf("stat::peak_rss_mb:              %zd\n", GetPeakRSSMb());
 }
 
@@ -455,7 +454,7 @@
       static_cast<long>(static_cast<double>(TimeOfLongestUnitInSeconds) * 1.1);
   if (TimeOfUnit > Threshhold && TimeOfUnit >= Options.ReportSlowUnits) {
     TimeOfLongestUnitInSeconds = TimeOfUnit;
-    Printf("Slowest unit: %zd s:\n", TimeOfLongestUnitInSeconds);
+    Printf("Slowest unit: %ld s:\n", TimeOfLongestUnitInSeconds);
     WriteUnitToFileWithPrefix({Data, Data + Size}, "slow-unit-");
   }
 }