diff --git a/src/catch2/reporters/catch_reporter_combined_tu.cpp b/src/catch2/reporters/catch_reporter_combined_tu.cpp
index a05b4998..42974249 100644
--- a/src/catch2/reporters/catch_reporter_combined_tu.cpp
+++ b/src/catch2/reporters/catch_reporter_combined_tu.cpp
@@ -69,11 +69,13 @@ namespace Catch {
         // Save previous errno, to prevent sprintf from overwriting it
         ErrnoGuard guard;
 #ifdef _MSC_VER
-        sprintf_s( buffer, "%.3f", duration );
+        size_t printedLength = static_cast<size_t>(
+            sprintf_s( buffer, "%.3f", duration ) );
 #else
-        std::snprintf( buffer, maxDoubleSize, "%.3f", duration );
+        size_t printedLength = static_cast<size_t>(
+            std::snprintf( buffer, maxDoubleSize, "%.3f", duration ) );
 #endif
-        return std::string( buffer );
+        return std::string( buffer, printedLength );
     }
 
     bool shouldShowDuration( IConfig const& config, double duration ) {
diff --git a/src/catch2/reporters/catch_reporter_junit.cpp b/src/catch2/reporters/catch_reporter_junit.cpp
index c5d0929c..7570d9ea 100644
--- a/src/catch2/reporters/catch_reporter_junit.cpp
+++ b/src/catch2/reporters/catch_reporter_junit.cpp
@@ -38,7 +38,7 @@ namespace Catch {
 
             std::strftime(timeStamp, timeStampSize, fmt, &timeInfo);
 
-            return std::string(timeStamp);
+            return std::string(timeStamp, timeStampSize - 1);
         }
 
         std::string fileNameTag(std::vector<Tag> const& tags) {