diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index ebe2d1c84b5..7a708089444 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -26907,6 +26907,14 @@ namespace ts {
                 const lhsType = getTypeOfExpression(e.expression);
                 return isPrivateIdentifier(e.name) ? tryGetPrivateIdentifierPropertyOfType(lhsType, e.name) : getPropertyOfType(lhsType, e.name.escapedText);
             }
+            if (isElementAccessExpression(e)) {
+                const propType = checkExpressionCached(e.argumentExpression);
+                if (!isTypeUsableAsPropertyName(propType)) {
+                    return undefined;
+                }
+                const lhsType = getTypeOfExpression(e.expression);
+                return getPropertyOfType(lhsType, getPropertyNameFromType(propType));
+            }
             return undefined;
 
             function tryGetPrivateIdentifierPropertyOfType(type: Type, id: PrivateIdentifier) {
diff --git a/tests/baselines/reference/classPropInitializationInferenceWithElementAccess.symbols b/tests/baselines/reference/classPropInitializationInferenceWithElementAccess.symbols
new file mode 100644
index 00000000000..d8916efa2bf
--- /dev/null
+++ b/tests/baselines/reference/classPropInitializationInferenceWithElementAccess.symbols
@@ -0,0 +1,41 @@
+=== tests/cases/compiler/classPropInitializationInferenceWithElementAccess.ts ===
+// repro #49339
+export class Cls {
+>Cls : Symbol(Cls, Decl(classPropInitializationInferenceWithElementAccess.ts, 0, 0))
+
+    x;
+>x : Symbol(Cls.x, Decl(classPropInitializationInferenceWithElementAccess.ts, 1, 18))
+
+    y;
+>y : Symbol(Cls.y, Decl(classPropInitializationInferenceWithElementAccess.ts, 2, 6))
+
+    z;
+>z : Symbol(Cls.z, Decl(classPropInitializationInferenceWithElementAccess.ts, 3, 6))
+    
+    0;
+>0 : Symbol(Cls[0], Decl(classPropInitializationInferenceWithElementAccess.ts, 4, 6))
+
+    constructor(seed: number) {
+>seed : Symbol(seed, Decl(classPropInitializationInferenceWithElementAccess.ts, 8, 16))
+
+        this['x'] = [seed];
+>this : Symbol(Cls, Decl(classPropInitializationInferenceWithElementAccess.ts, 0, 0))
+>'x' : Symbol(Cls.x, Decl(classPropInitializationInferenceWithElementAccess.ts, 1, 18))
+>seed : Symbol(seed, Decl(classPropInitializationInferenceWithElementAccess.ts, 8, 16))
+
+        this['y'] = { seed };
+>this : Symbol(Cls, Decl(classPropInitializationInferenceWithElementAccess.ts, 0, 0))
+>'y' : Symbol(Cls.y, Decl(classPropInitializationInferenceWithElementAccess.ts, 2, 6))
+>seed : Symbol(seed, Decl(classPropInitializationInferenceWithElementAccess.ts, 10, 21))
+
+        this['z'] = `${seed}`;
+>this : Symbol(Cls, Decl(classPropInitializationInferenceWithElementAccess.ts, 0, 0))
+>'z' : Symbol(Cls.z, Decl(classPropInitializationInferenceWithElementAccess.ts, 3, 6))
+>seed : Symbol(seed, Decl(classPropInitializationInferenceWithElementAccess.ts, 8, 16))
+
+        this[0] = [seed];
+>this : Symbol(Cls, Decl(classPropInitializationInferenceWithElementAccess.ts, 0, 0))
+>0 : Symbol(Cls[0], Decl(classPropInitializationInferenceWithElementAccess.ts, 4, 6))
+>seed : Symbol(seed, Decl(classPropInitializationInferenceWithElementAccess.ts, 8, 16))
+    }
+}
diff --git a/tests/baselines/reference/classPropInitializationInferenceWithElementAccess.types b/tests/baselines/reference/classPropInitializationInferenceWithElementAccess.types
new file mode 100644
index 00000000000..397394b2350
--- /dev/null
+++ b/tests/baselines/reference/classPropInitializationInferenceWithElementAccess.types
@@ -0,0 +1,53 @@
+=== tests/cases/compiler/classPropInitializationInferenceWithElementAccess.ts ===
+// repro #49339
+export class Cls {
+>Cls : Cls
+
+    x;
+>x : number[]
+
+    y;
+>y : { seed: number; }
+
+    z;
+>z : string
+    
+    0;
+>0 : number[]
+
+    constructor(seed: number) {
+>seed : number
+
+        this['x'] = [seed];
+>this['x'] = [seed] : number[]
+>this['x'] : number[]
+>this : this
+>'x' : "x"
+>[seed] : number[]
+>seed : number
+
+        this['y'] = { seed };
+>this['y'] = { seed } : { seed: number; }
+>this['y'] : { seed: number; }
+>this : this
+>'y' : "y"
+>{ seed } : { seed: number; }
+>seed : number
+
+        this['z'] = `${seed}`;
+>this['z'] = `${seed}` : string
+>this['z'] : string
+>this : this
+>'z' : "z"
+>`${seed}` : string
+>seed : number
+
+        this[0] = [seed];
+>this[0] = [seed] : number[]
+>this[0] : number[]
+>this : this
+>0 : 0
+>[seed] : number[]
+>seed : number
+    }
+}
diff --git a/tests/cases/compiler/classPropInitializationInferenceWithElementAccess.ts b/tests/cases/compiler/classPropInitializationInferenceWithElementAccess.ts
new file mode 100644
index 00000000000..7bd1920a7d6
--- /dev/null
+++ b/tests/cases/compiler/classPropInitializationInferenceWithElementAccess.ts
@@ -0,0 +1,19 @@
+// @noEmit: true
+// @strict: true
+
+// repro #49339
+export class Cls {
+    x;
+    y;
+    z;
+    
+    0;
+
+    constructor(seed: number) {
+        this['x'] = [seed];
+        this['y'] = { seed };
+        this['z'] = `${seed}`;
+
+        this[0] = [seed];
+    }
+}
\ No newline at end of file