diff --git a/rts/System/Log/DefaultFilter.cpp b/rts/System/Log/DefaultFilter.cpp
index cf0c3939d29..3ec33410cf1 100644
--- a/rts/System/Log/DefaultFilter.cpp
+++ b/rts/System/Log/DefaultFilter.cpp
@@ -157,13 +157,15 @@ void log_filter_section_setMinLevel(int level, const char* section)
 	// (same string but will not become garbage)
 	section = *registeredSection;
 
-	if (level == log_filter_section_getDefaultMinLevel(section)) {
-		using P = decltype(log_filter::sectionMinLevels)::value_type;
-
-		const auto sectionComparer = [](const P& a, const P& b) { return (log_filter_section_compare()(a.first, b.first)); };
-		const auto sectionMinLevel = std::lower_bound(secLvls.begin(), secLvls.begin() + log_filter::numLevels, P{section, 0}, sectionComparer);
+	// locate any existing override for this section (the array is kept sorted)
+	using P = decltype(log_filter::sectionMinLevels)::value_type;
+	const auto sectionComparer = [](const P& a, const P& b) { return (log_filter_section_compare()(a.first, b.first)); };
+	const auto sectionMinLevel = std::lower_bound(secLvls.begin(), secLvls.begin() + log_filter::numLevels, P{section, 0}, sectionComparer);
+	const bool exists = (sectionMinLevel != (secLvls.begin() + log_filter::numLevels) && strcmp(sectionMinLevel->first, section) == 0);
 
-		if (sectionMinLevel == (secLvls.begin() + log_filter::numLevels) || strcmp(sectionMinLevel->first, section) != 0)
+	if (level == log_filter_section_getDefaultMinLevel(section)) {
+		// back to default: drop any existing override (nothing to do otherwise)
+		if (!exists)
 			return;
 
 		// erase
@@ -175,6 +177,13 @@ void log_filter_section_setMinLevel(int level, const char* section)
 		return;
 	}
 
+	// non-default: update any existing override in-place
+	if (exists) {
+		sectionMinLevel->second = level;
+		return;
+	}
+
+	// add a net new override
 	secLvls[log_filter::numLevels++] = {section, level};
 
 	// swap into position
diff --git a/test/engine/System/Log/TestILog.cpp b/test/engine/System/Log/TestILog.cpp
index cb8d4b3e4a1..7b7d1345f0c 100644
--- a/test/engine/System/Log/TestILog.cpp
+++ b/test/engine/System/Log/TestILog.cpp
@@ -3,6 +3,7 @@
 #include "System/Log/FileSink.h"
 #include "System/Log/StreamSink.h"
 #include "System/Log/LogUtil.h"
+#include "System/Log/DefaultFilter.h"
 
 #include <catch_amalgamated.hpp>
 
@@ -231,3 +232,33 @@ TEST_CASE("IsEnabled")
 	TLOG_SL(   "other-one-time-section", L_DEBUG, "Testing LOG_IS_ENABLED_S");
 }
 
+
+// Regression for the duplicate-entry leak in log_filter_section_setMinLevel.
+// Setting a section to a non-default level used to *append* a new row every call
+// instead of updating the existing one, so repeated changes to one section filled
+// the fixed-size sectionMinLevels table and then made *all* section-level changes
+// silently fail ("too many section-levels").
+TEST_CASE("SectionMinLevelNoDuplicateLeak")
+{
+	// non-default levels for these (non-default) sections; restored at the end
+	const int savedDefined = log_filter_section_getMinLevel(LOG_SECTION_DEFINED);
+	const int savedOneTime = log_filter_section_getMinLevel(LOG_SECTION_ONE_TIME_0);
+
+	// hammer one section far more than the table could ever hold
+	for (int i = 0; i < 300; ++i)
+		log_filter_section_setMinLevel((i & 1) ? LOG_LEVEL_WARNING : LOG_LEVEL_ERROR, LOG_SECTION_DEFINED);
+
+	// the most recent value wins (a single, updated-in-place entry)
+	log_filter_section_setMinLevel(LOG_LEVEL_ERROR, LOG_SECTION_DEFINED);
+	CHECK(log_filter_section_getMinLevel(LOG_SECTION_DEFINED) == LOG_LEVEL_ERROR);
+
+	// and a *different* section must still be settable: with the old append bug
+	// the table is saturated by now and this set would be dropped
+	log_filter_section_setMinLevel(LOG_LEVEL_WARNING, LOG_SECTION_ONE_TIME_0);
+	CHECK(log_filter_section_getMinLevel(LOG_SECTION_ONE_TIME_0) == LOG_LEVEL_WARNING);
+
+	// restore original levels (setting back to default takes the erase path)
+	log_filter_section_setMinLevel(savedDefined, LOG_SECTION_DEFINED);
+	log_filter_section_setMinLevel(savedOneTime, LOG_SECTION_ONE_TIME_0);
+}
+