diff --git a/java/kotlin-extractor/src/main/kotlin/KotlinFileExtractor.kt b/java/kotlin-extractor/src/main/kotlin/KotlinFileExtractor.kt
index a318528010f..49705f57d2e 100644
--- a/java/kotlin-extractor/src/main/kotlin/KotlinFileExtractor.kt
+++ b/java/kotlin-extractor/src/main/kotlin/KotlinFileExtractor.kt
@@ -3084,9 +3084,10 @@ open class KotlinFileExtractor(
         id: Label<out DbExpr>,
         c: IrCall,
         callable: Label<out DbCallable>,
-        enclosingStmt: Label<out DbStmt>
+        enclosingStmt: Label<out DbStmt>,
+        customLocId: Label<DbLocation>? = null
     ) {
-        val locId = tw.getLocation(c)
+        val locId = customLocId ?: tw.getLocation(c)
         extractExprContext(id, locId, callable, enclosingStmt)
 
         val dr = c.dispatchReceiver
@@ -4584,7 +4585,12 @@ open class KotlinFileExtractor(
                     val type = useType(c.type)
                     tw.writeExprs_notnullexpr(id, type.javaResult.id, parent, idx)
                     tw.writeExprsKotlinType(id, type.kotlinResult.id)
-                    unaryOp(id, c, callable, enclosingStmt)
+                    // In K1 mode the IrCall.startOffset for !! points to the '!' character rather
+                    // than the start of the operand. Use the operand's startOffset instead so that
+                    // the NotNullExpr spans from the operand to the end of '!!'.
+                    val operandStart = c.codeQlGetValueArgument(0)?.startOffset?.takeIf { it >= 0 }
+                    val notNullLocId = if (operandStart != null && c.endOffset >= 0) tw.getLocation(operandStart, c.endOffset) else null
+                    unaryOp(id, c, callable, enclosingStmt, notNullLocId)
                 }
                 isBuiltinCallInternal(c, "THROW_CCE") -> {
                     // TODO
diff --git a/java/ql/test-kotlin1/library-tests/controlflow/basic/bbStmts.expected b/java/ql/test-kotlin1/library-tests/controlflow/basic/bbStmts.expected
index 61d80537663..783ea4712fe 100644
--- a/java/ql/test-kotlin1/library-tests/controlflow/basic/bbStmts.expected
+++ b/java/ql/test-kotlin1/library-tests/controlflow/basic/bbStmts.expected
@@ -251,18 +251,18 @@
 | Test.kt:91:1:98:1 | Entry | 3 | Test.kt:92:6:95:2 | { ... } |
 | Test.kt:91:1:98:1 | Entry | 4 | Test.kt:93:7:93:7 | var ...; |
 | Test.kt:91:1:98:1 | Entry | 5 | Test.kt:93:7:93:7 | Before x |
-| Test.kt:91:1:98:1 | Entry | 6 | Test.kt:93:12:93:13 | Before ...!! |
+| Test.kt:91:1:98:1 | Entry | 6 | Test.kt:93:11:93:13 | Before ...!! |
 | Test.kt:91:1:98:1 | Entry | 7 | Test.kt:93:11:93:11 | o |
-| Test.kt:91:1:98:1 | Entry | 8 | Test.kt:93:12:93:13 | ...!! |
+| Test.kt:91:1:98:1 | Entry | 8 | Test.kt:93:11:93:13 | ...!! |
 | Test.kt:91:1:98:1 | Exit | 0 | Test.kt:91:1:98:1 | Exit |
 | Test.kt:91:1:98:1 | Normal Exit | 0 | Test.kt:91:1:98:1 | Normal Exit |
-| Test.kt:93:12:93:13 | After ...!! | 0 | Test.kt:93:12:93:13 | After ...!! |
-| Test.kt:93:12:93:13 | After ...!! | 1 | Test.kt:93:7:93:7 | x |
-| Test.kt:93:12:93:13 | After ...!! | 2 | Test.kt:93:7:93:7 | After x |
-| Test.kt:93:12:93:13 | After ...!! | 3 | Test.kt:93:7:93:7 | After var ...; |
-| Test.kt:93:12:93:13 | After ...!! | 4 | Test.kt:94:3:94:10 | Before return ... |
-| Test.kt:93:12:93:13 | After ...!! | 5 | Test.kt:94:10:94:10 | 1 |
-| Test.kt:93:12:93:13 | After ...!! | 6 | Test.kt:94:3:94:10 | return ... |
+| Test.kt:93:11:93:13 | After ...!! | 0 | Test.kt:93:11:93:13 | After ...!! |
+| Test.kt:93:11:93:13 | After ...!! | 1 | Test.kt:93:7:93:7 | x |
+| Test.kt:93:11:93:13 | After ...!! | 2 | Test.kt:93:7:93:7 | After x |
+| Test.kt:93:11:93:13 | After ...!! | 3 | Test.kt:93:7:93:7 | After var ...; |
+| Test.kt:93:11:93:13 | After ...!! | 4 | Test.kt:94:3:94:10 | Before return ... |
+| Test.kt:93:11:93:13 | After ...!! | 5 | Test.kt:94:10:94:10 | 1 |
+| Test.kt:93:11:93:13 | After ...!! | 6 | Test.kt:94:3:94:10 | return ... |
 | Test.kt:95:4:97:2 | catch (...) | 0 | Test.kt:95:4:97:2 | catch (...) |
 | Test.kt:95:4:97:2 | catch (...) | 1 | Test.kt:95:11:95:33 | e |
 | Test.kt:95:11:95:33 | After e [match] | 0 | Test.kt:95:11:95:33 | After e [match] |
diff --git a/java/ql/test-kotlin1/library-tests/controlflow/basic/getASuccessor.expected b/java/ql/test-kotlin1/library-tests/controlflow/basic/getASuccessor.expected
index 5f4663d14b5..67f03324b42 100644
--- a/java/ql/test-kotlin1/library-tests/controlflow/basic/getASuccessor.expected
+++ b/java/ql/test-kotlin1/library-tests/controlflow/basic/getASuccessor.expected
@@ -150,9 +150,9 @@
 | Test.kt:92:6:95:2 | { ... } | BlockStmt | Test.kt:93:7:93:7 | var ...; | LocalVariableDeclStmt |
 | Test.kt:93:7:93:7 | var ...; | LocalVariableDeclStmt | Test.kt:93:11:93:11 | o | VarAccess |
 | Test.kt:93:7:93:7 | x | LocalVariableDeclExpr | Test.kt:94:10:94:10 | 1 | IntegerLiteral |
-| Test.kt:93:11:93:11 | o | VarAccess | Test.kt:93:12:93:13 | ...!! | NotNullExpr |
-| Test.kt:93:12:93:13 | ...!! | NotNullExpr | Test.kt:93:7:93:7 | x | LocalVariableDeclExpr |
-| Test.kt:93:12:93:13 | ...!! | NotNullExpr | Test.kt:95:4:97:2 | catch (...) | CatchClause |
+| Test.kt:93:11:93:11 | o | VarAccess | Test.kt:93:11:93:13 | ...!! | NotNullExpr |
+| Test.kt:93:11:93:13 | ...!! | NotNullExpr | Test.kt:93:7:93:7 | x | LocalVariableDeclExpr |
+| Test.kt:93:11:93:13 | ...!! | NotNullExpr | Test.kt:95:4:97:2 | catch (...) | CatchClause |
 | Test.kt:94:3:94:10 | return ... | ReturnStmt | Test.kt:91:1:98:1 | Normal Exit | Method |
 | Test.kt:94:10:94:10 | 1 | IntegerLiteral | Test.kt:94:3:94:10 | return ... | ReturnStmt |
 | Test.kt:95:4:97:2 | catch (...) | CatchClause | Test.kt:95:11:95:33 | e | LocalVariableDeclExpr |
diff --git a/java/ql/test-kotlin1/library-tests/exprs/binop.expected b/java/ql/test-kotlin1/library-tests/exprs/binop.expected
index f69701028d5..c0d798a2679 100644
--- a/java/ql/test-kotlin1/library-tests/exprs/binop.expected
+++ b/java/ql/test-kotlin1/library-tests/exprs/binop.expected
@@ -96,8 +96,8 @@
 | exprs.kt:141:12:141:20 | ... + ... | exprs.kt:141:12:141:14 | 123 | exprs.kt:141:18:141:20 | 456 |
 | exprs.kt:167:8:167:16 | ... (value not-equals) ... | exprs.kt:167:8:167:8 | r | exprs.kt:167:13:167:16 | null |
 | exprs.kt:196:31:196:37 | ... + ... | exprs.kt:196:31:196:32 | getA1(...) | exprs.kt:196:36:196:37 | a2 |
-| exprs.kt:211:20:211:29 | ... + ... | exprs.kt:211:20:211:21 | ...!! | exprs.kt:211:28:211:28 | 5 |
-| exprs.kt:212:19:212:25 | ... + ... | exprs.kt:212:20:212:21 | ...!! | exprs.kt:212:25:212:25 | 5 |
+| exprs.kt:211:20:211:29 | ... + ... | exprs.kt:211:19:211:21 | ...!! | exprs.kt:211:28:211:28 | 5 |
+| exprs.kt:212:19:212:25 | ... + ... | exprs.kt:212:19:212:21 | ...!! | exprs.kt:212:25:212:25 | 5 |
 | exprs.kt:230:12:230:47 | ... (value equals) ... | exprs.kt:230:12:230:27 | notNullPrimitive | exprs.kt:230:32:230:47 | notNullPrimitive |
 | exprs.kt:231:12:231:48 | ... (value equals) ... | exprs.kt:231:12:231:27 | notNullPrimitive | exprs.kt:231:32:231:48 | nullablePrimitive |
 | exprs.kt:232:12:232:49 | ... (value equals) ... | exprs.kt:232:12:232:28 | nullablePrimitive | exprs.kt:232:33:232:49 | nullablePrimitive |
diff --git a/java/ql/test-kotlin1/library-tests/exprs/exprs.expected b/java/ql/test-kotlin1/library-tests/exprs/exprs.expected
index 83fbd974893..a0ab1de18b9 100644
--- a/java/ql/test-kotlin1/library-tests/exprs/exprs.expected
+++ b/java/ql/test-kotlin1/library-tests/exprs/exprs.expected
@@ -1572,7 +1572,7 @@
 | exprs.kt:201:22:201:28 | Object | file://:0:0:0:0 | <none> | TypeAccess |
 | exprs.kt:202:9:202:9 | y | exprs.kt:201:1:203:1 | notNullAssertion | LocalVariableDeclExpr |
 | exprs.kt:202:18:202:18 | x | exprs.kt:201:1:203:1 | notNullAssertion | VarAccess |
-| exprs.kt:202:19:202:20 | ...!! | exprs.kt:201:1:203:1 | notNullAssertion | NotNullExpr |
+| exprs.kt:202:18:202:20 | ...!! | exprs.kt:201:1:203:1 | notNullAssertion | NotNullExpr |
 | exprs.kt:206:5:217:5 | Unit | file://:0:0:0:0 | <none> | TypeAccess |
 | exprs.kt:206:11:206:18 | Object | file://:0:0:0:0 | <none> | TypeAccess |
 | exprs.kt:206:21:206:30 | String | file://:0:0:0:0 | <none> | TypeAccess |
@@ -1592,13 +1592,13 @@
 | exprs.kt:210:23:210:23 | 5 | exprs.kt:206:5:217:5 | x | IntegerLiteral |
 | exprs.kt:211:13:211:14 | b2 | exprs.kt:206:5:217:5 | x | LocalVariableDeclExpr |
 | exprs.kt:211:19:211:19 | s | exprs.kt:206:5:217:5 | x | VarAccess |
-| exprs.kt:211:20:211:21 | ...!! | exprs.kt:206:5:217:5 | x | NotNullExpr |
+| exprs.kt:211:19:211:21 | ...!! | exprs.kt:206:5:217:5 | x | NotNullExpr |
 | exprs.kt:211:20:211:29 | ... + ... | exprs.kt:206:5:217:5 | x | AddExpr |
 | exprs.kt:211:28:211:28 | 5 | exprs.kt:206:5:217:5 | x | IntegerLiteral |
 | exprs.kt:212:13:212:14 | b3 | exprs.kt:206:5:217:5 | x | LocalVariableDeclExpr |
 | exprs.kt:212:19:212:19 | s | exprs.kt:206:5:217:5 | x | VarAccess |
+| exprs.kt:212:19:212:21 | ...!! | exprs.kt:206:5:217:5 | x | NotNullExpr |
 | exprs.kt:212:19:212:25 | ... + ... | exprs.kt:206:5:217:5 | x | AddExpr |
-| exprs.kt:212:20:212:21 | ...!! | exprs.kt:206:5:217:5 | x | NotNullExpr |
 | exprs.kt:212:25:212:25 | 5 | exprs.kt:206:5:217:5 | x | IntegerLiteral |
 | exprs.kt:213:13:213:14 | c0 | exprs.kt:206:5:217:5 | x | LocalVariableDeclExpr |
 | exprs.kt:213:18:213:36 | Color | exprs.kt:206:5:217:5 | x | TypeAccess |
diff --git a/java/ql/test-kotlin1/library-tests/exprs/unaryOp.expected b/java/ql/test-kotlin1/library-tests/exprs/unaryOp.expected
index 03b5d64a7f4..487226320cc 100644
--- a/java/ql/test-kotlin1/library-tests/exprs/unaryOp.expected
+++ b/java/ql/test-kotlin1/library-tests/exprs/unaryOp.expected
@@ -2,9 +2,9 @@
 | exprs.kt:32:15:32:26 | !... | exprs.kt:32:15:32:26 | contains(...) |
 | exprs.kt:79:15:79:22 | ~... | exprs.kt:79:15:79:16 | lx |
 | exprs.kt:121:14:121:16 | !... | exprs.kt:121:15:121:16 | b1 |
-| exprs.kt:202:19:202:20 | ...!! | exprs.kt:202:18:202:18 | x |
-| exprs.kt:211:20:211:21 | ...!! | exprs.kt:211:19:211:19 | s |
-| exprs.kt:212:20:212:21 | ...!! | exprs.kt:212:19:212:19 | s |
+| exprs.kt:202:18:202:20 | ...!! | exprs.kt:202:18:202:18 | x |
+| exprs.kt:211:19:211:21 | ...!! | exprs.kt:211:19:211:19 | s |
+| exprs.kt:212:19:212:21 | ...!! | exprs.kt:212:19:212:19 | s |
 | exprs.kt:286:5:286:6 | -... | exprs.kt:286:6:286:6 | i |
 | exprs.kt:287:5:287:6 | +... | exprs.kt:287:6:287:6 | i |
 | exprs.kt:288:5:288:6 | -... | exprs.kt:288:6:288:6 | d |