diff --git a/go/otel/otelstef/exphistogramvalue.go b/go/otel/otelstef/exphistogramvalue.go
index ef063515..d22a9076 100644
--- a/go/otel/otelstef/exphistogramvalue.go
+++ b/go/otel/otelstef/exphistogramvalue.go
@@ -101,6 +101,7 @@ func (s *ExpHistogramValue) reset() {
 	s.positiveBuckets.reset()
 	s.negativeBuckets.reset()
 	s.zeroThreshold = 0.0
+	s.optionalFieldsPresent = 0
 }
 
 // fixParent sets the parentModifiedFields pointer to the supplied value.
diff --git a/go/otel/otelstef/histogramvalue.go b/go/otel/otelstef/histogramvalue.go
index 67c4f3d0..cc82184a 100644
--- a/go/otel/otelstef/histogramvalue.go
+++ b/go/otel/otelstef/histogramvalue.go
@@ -87,6 +87,7 @@ func (s *HistogramValue) reset() {
 	s.min = 0.0
 	s.max = 0.0
 	s.bucketCounts.reset()
+	s.optionalFieldsPresent = 0
 }
 
 // fixParent sets the parentModifiedFields pointer to the supplied value.
diff --git a/java/src/main/java/com/example/otelstef/ExpHistogramValue.java b/java/src/main/java/com/example/otelstef/ExpHistogramValue.java
index 9ec1db94..1857e949 100644
--- a/java/src/main/java/com/example/otelstef/ExpHistogramValue.java
+++ b/java/src/main/java/com/example/otelstef/ExpHistogramValue.java
@@ -90,6 +90,7 @@ void reset() {
             negativeBuckets.reset();
         }
         zeroThreshold = 0.0;
+        optionalFieldsPresent = 0;
     }
 
     
diff --git a/java/src/main/java/com/example/otelstef/HistogramValue.java b/java/src/main/java/com/example/otelstef/HistogramValue.java
index fa7d02f6..b740956f 100644
--- a/java/src/main/java/com/example/otelstef/HistogramValue.java
+++ b/java/src/main/java/com/example/otelstef/HistogramValue.java
@@ -72,6 +72,7 @@ void reset() {
         if (bucketCounts != null) {
             bucketCounts.reset();
         }
+        optionalFieldsPresent = 0;
     }
 
     
diff --git a/stefc/generator/testdata/optional_reset_fail.stef b/stefc/generator/testdata/optional_reset_fail.stef
new file mode 100644
index 00000000..795932f5
--- /dev/null
+++ b/stefc/generator/testdata/optional_reset_fail.stef
@@ -0,0 +1,14 @@
+// This schema was failing (for seed 1765233907441407000) because
+// optional struct fields were not reset correctly by reset() method.
+package com.example.gentest.optional_reset_fail
+
+multimap MultiMap1 {
+  key Struct1
+  value int64
+}
+
+struct Struct1 root {
+  Field1 bytes optional
+  Field2 MultiMap1
+  Field3 Struct1 optional
+}
diff --git a/stefc/generator/testdata/seeds/optional_reset_fail_Struct1_seeds.txt b/stefc/generator/testdata/seeds/optional_reset_fail_Struct1_seeds.txt
new file mode 100644
index 00000000..696b53d2
--- /dev/null
+++ b/stefc/generator/testdata/seeds/optional_reset_fail_Struct1_seeds.txt
@@ -0,0 +1 @@
+1765234703981295000
diff --git a/stefc/templates/go/struct.go.tmpl b/stefc/templates/go/struct.go.tmpl
index a74128c3..a7397fce 100644
--- a/stefc/templates/go/struct.go.tmpl
+++ b/stefc/templates/go/struct.go.tmpl
@@ -138,6 +138,9 @@ func (s *{{ $.StructName }}) reset() {
     {{- end -}}
     {{- end -}}
     {{- end -}}
+    {{- if .OptionalFieldCount}}
+    s.optionalFieldsPresent = 0
+    {{- end}}
 }
 
 // fixParent sets the parentModifiedFields pointer to the supplied value.
diff --git a/stefc/templates/java/struct.java.tmpl b/stefc/templates/java/struct.java.tmpl
index 647ea844..2d747c09 100644
--- a/stefc/templates/java/struct.java.tmpl
+++ b/stefc/templates/java/struct.java.tmpl
@@ -79,6 +79,9 @@ public class {{ .StructName }} {
 
         {{- end }}
         {{- end }}
+        {{- if .OptionalFieldCount}}
+        optionalFieldsPresent = 0;
+        {{- end}}
     }
 
     {{ range .Fields }}