diff --git a/utbot-framework/src/main/kotlin/org/utbot/sarif/DataClasses.kt b/utbot-framework/src/main/kotlin/org/utbot/sarif/DataClasses.kt
index e71294914d..01ed9ca331 100644
--- a/utbot-framework/src/main/kotlin/org/utbot/sarif/DataClasses.kt
+++ b/utbot-framework/src/main/kotlin/org/utbot/sarif/DataClasses.kt
@@ -203,7 +203,9 @@ data class SarifArtifact(
     val uriBaseId: String = "%SRCROOT%"
 )
 
-// all fields should be one-based
+/**
+ * All fields should be one-based.
+ */
 data class SarifRegion(
     val startLine: Int,
     val endLine: Int? = null,
@@ -214,13 +216,20 @@ data class SarifRegion(
         /**
          * Makes [startColumn] the first non-whitespace character in [startLine] in the [text].
          * If the [text] contains less than [startLine] lines, [startColumn] == null.
+         * @param startLine should be one-based
          */
         fun withStartLine(text: String, startLine: Int): SarifRegion {
             val neededLine = text.split('\n').getOrNull(startLine - 1) // to zero-based
             val startColumn = neededLine?.run {
                 takeWhile { it.toString().isBlank() }.length + 1 // to one-based
             }
-            return SarifRegion(startLine = startLine, startColumn = startColumn)
+            val safeStartLine = if (startLine < 1) {
+                logger.warn { "For some reason startLine < 1, so now it is equal to 1" }
+                1 // we don't want to fail, so just set the line number to 1
+            } else {
+                startLine
+            }
+            return SarifRegion(startLine = safeStartLine, startColumn = startColumn)
         }
     }
 }
diff --git a/utbot-framework/src/main/kotlin/org/utbot/sarif/SarifReport.kt b/utbot-framework/src/main/kotlin/org/utbot/sarif/SarifReport.kt
index 94de6244cc..1df35ccd1e 100644
--- a/utbot-framework/src/main/kotlin/org/utbot/sarif/SarifReport.kt
+++ b/utbot-framework/src/main/kotlin/org/utbot/sarif/SarifReport.kt
@@ -1,5 +1,6 @@
 package org.utbot.sarif
 
+import mu.KotlinLogging
 import org.utbot.common.PathUtil.fileExtension
 import org.utbot.common.PathUtil.toPath
 import org.utbot.framework.UtSettings
@@ -7,6 +8,8 @@ import org.utbot.framework.plugin.api.*
 import java.nio.file.Path
 import kotlin.io.path.nameWithoutExtension
 
+internal val logger = KotlinLogging.logger {}
+
 /**
  * Used for the SARIF report creation by given test cases and generated tests code.
  * SARIF is a JSON-based format for presenting static analyzer results.
@@ -328,7 +331,7 @@ class SarifReport(
                 message = Message("$classFqn.$methodName($sourceFileName:$lineNumber)"),
                 physicalLocation = SarifPhysicalLocation(
                     SarifArtifact(uri = sourceFilePath),
-                    SarifRegion(startLine = lineNumber)
+                    SarifRegion(startLine = lineNumber) // lineNumber is one-based
                 )
             ))
         }
@@ -440,7 +443,7 @@ class SarifReport(
         val lastCoveredInstruction = coveredInstructions?.lastOrNull()
         if (lastCoveredInstruction != null)
             return Pair(
-                lastCoveredInstruction.lineNumber,
+                lastCoveredInstruction.lineNumber, // .lineNumber is one-based
                 lastCoveredInstruction.className.replace('/', '.')
             )
 
@@ -448,7 +451,7 @@ class SarifReport(
         val lastPathElementLineNumber = try {
             // path/fullPath might be empty when engine executes in another process -
             // soot entities cannot be passed to the main process because kryo cannot deserialize them
-            (utExecution as? UtSymbolicExecution)?.path?.lastOrNull()?.stmt?.javaSourceStartLineNumber
+            (utExecution as? UtSymbolicExecution)?.path?.lastOrNull()?.stmt?.javaSourceStartLineNumber // one-based
         } catch (t: Throwable) {
             null
         }