diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index ed16a1be8..b1433a06c 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -27,6 +27,7 @@ The following tip changes can be tested by building VictoriaMetrics components f
 * BUGFIX: [vmagent](https://docs.victoriametrics.com/vmagent.html): do not send stale markers to remote storage for series exceeding the configured [series limit](https://docs.victoriametrics.com/vmagent.html#cardinality-limiter). See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3660).
 * BUGFIX: [vmagent](https://docs.victoriametrics.com/vmagent.html): properly apply [series limit](https://docs.victoriametrics.com/vmagent.html#cardinality-limiter) when [staleness tracking](https://docs.victoriametrics.com/vmagent.html#prometheus-staleness-markers) is disabled.
 * BUGFIX: [Pushgateway import](https://docs.victoriametrics.com/#how-to-import-data-in-prometheus-exposition-format): properly return `200 OK` HTTP response code. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3636).
+* BUGFIX: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): properly parse `M` and `Mi` suffixes as `1e6` multipliers in `1M` and `1Mi` numeric constants. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3664). The issue has been introduced in [v1.86.0](https://docs.victoriametrics.com/CHANGELOG.html#v1860).
 
 ## [v1.86.1](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.86.1)
 
diff --git a/go.mod b/go.mod
index 92937c54e..04b44b322 100644
--- a/go.mod
+++ b/go.mod
@@ -12,7 +12,7 @@ require (
 	// like https://github.com/valyala/fasthttp/commit/996610f021ff45fdc98c2ce7884d5fa4e7f9199b
 	github.com/VictoriaMetrics/fasthttp v1.1.0
 	github.com/VictoriaMetrics/metrics v1.23.1
-	github.com/VictoriaMetrics/metricsql v0.51.1
+	github.com/VictoriaMetrics/metricsql v0.51.2
 	github.com/aws/aws-sdk-go-v2 v1.17.3
 	github.com/aws/aws-sdk-go-v2/config v1.18.8
 	github.com/aws/aws-sdk-go-v2/feature/s3/manager v1.11.47
diff --git a/go.sum b/go.sum
index b92d01b20..eebce8771 100644
--- a/go.sum
+++ b/go.sum
@@ -69,8 +69,8 @@ github.com/VictoriaMetrics/fasthttp v1.1.0/go.mod h1:/7DMcogqd+aaD3G3Hg5kFgoFwlR
 github.com/VictoriaMetrics/metrics v1.18.1/go.mod h1:ArjwVz7WpgpegX/JpB0zpNF2h2232kErkEnzH1sxMmA=
 github.com/VictoriaMetrics/metrics v1.23.1 h1:/j8DzeJBxSpL2qSIdqnRFLvQQhbJyJbbEi22yMm7oL0=
 github.com/VictoriaMetrics/metrics v1.23.1/go.mod h1:rAr/llLpEnAdTehiNlUxKgnjcOuROSzpw0GvjpEbvFc=
-github.com/VictoriaMetrics/metricsql v0.51.1 h1:gmh3ZGCDrqUTdhUrr87eJOXMOputDYs1PtLwTfySTsI=
-github.com/VictoriaMetrics/metricsql v0.51.1/go.mod h1:6pP1ZeLVJHqJrHlF6Ij3gmpQIznSsgktEcZgsAWYel0=
+github.com/VictoriaMetrics/metricsql v0.51.2 h1:GCbxti0I46x3Ld/WhcUyawvLr6J0x90IaMftkjosHJI=
+github.com/VictoriaMetrics/metricsql v0.51.2/go.mod h1:6pP1ZeLVJHqJrHlF6Ij3gmpQIznSsgktEcZgsAWYel0=
 github.com/VividCortex/ewma v1.1.1/go.mod h1:2Tkkvm3sRDVXaiyucHiACn4cqf7DpdyLvmxzcbUokwA=
 github.com/VividCortex/ewma v1.2.0 h1:f58SaIzcDXrSy3kWaHNvuJgJ3Nmz59Zji6XoJR/q1ow=
 github.com/VividCortex/ewma v1.2.0/go.mod h1:nz4BbCtbLyFDeC9SUHbtcT5644juEuWfUAUnGx7j5l4=
diff --git a/vendor/github.com/VictoriaMetrics/metricsql/lexer.go b/vendor/github.com/VictoriaMetrics/metricsql/lexer.go
index c3aebd80d..f0dec0a82 100644
--- a/vendor/github.com/VictoriaMetrics/metricsql/lexer.go
+++ b/vendor/github.com/VictoriaMetrics/metricsql/lexer.go
@@ -289,6 +289,9 @@ func scanPositiveNumber(s string) (string, error) {
 }
 
 func scanNumMultiplier(s string) int {
+	if len(s) > 3 {
+		s = s[:3]
+	}
 	s = strings.ToLower(s)
 	switch true {
 	case strings.HasPrefix(s, "kib"):
@@ -616,7 +619,6 @@ func scanSingleDuration(s string, canBeNegative bool) int {
 	if len(s) == 0 {
 		return -1
 	}
-	s = strings.ToLower(s)
 	i := 0
 	if s[0] == '-' && canBeNegative {
 		i++
@@ -637,14 +639,26 @@ func scanSingleDuration(s string, canBeNegative bool) int {
 			return -1
 		}
 	}
-	switch s[i] {
+	switch unicode.ToLower(rune(s[i])) {
 	case 'm':
-		if i+1 < len(s) && s[i+1] == 's' {
-			// duration in ms
-			return i + 2
+		if i+1 < len(s) {
+			switch unicode.ToLower(rune(s[i+1])) {
+			case 's':
+				// duration in ms
+				return i + 2
+			case 'i', 'b':
+				// This is not a duration, but Mi or MB suffix.
+				// See parsePositiveNumber() and https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3664
+				return -1
+			}
 		}
-		// duration in minutes
-		return i + 1
+		// Allow small m for durtion in minutes.
+		// Big M means 1e6.
+		// See parsePositiveNumber() and https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3664
+		if s[i] == 'm' {
+			return i + 1
+		}
+		return -1
 	case 's', 'h', 'd', 'w', 'y', 'i':
 		return i + 1
 	default:
diff --git a/vendor/modules.txt b/vendor/modules.txt
index bf77ddb3d..e32545b3c 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -70,7 +70,7 @@ github.com/VictoriaMetrics/fasthttp/stackless
 # github.com/VictoriaMetrics/metrics v1.23.1
 ## explicit; go 1.15
 github.com/VictoriaMetrics/metrics
-# github.com/VictoriaMetrics/metricsql v0.51.1
+# github.com/VictoriaMetrics/metricsql v0.51.2
 ## explicit; go 1.13
 github.com/VictoriaMetrics/metricsql
 github.com/VictoriaMetrics/metricsql/binaryop