diff --git a/src/Type/ArrayType.php b/src/Type/ArrayType.php
index a951f13c24..b24fbc64fc 100644
--- a/src/Type/ArrayType.php
+++ b/src/Type/ArrayType.php
@@ -484,10 +484,10 @@ public function fillKeysArray(Type $valueType): Type
 				return $stringKeyType;
 			}
 
-			return new ArrayType($stringKeyType, $valueType);
+			return new ArrayType($stringKeyType->toArrayKey(), $valueType);
 		}
 
-		return new ArrayType($itemType, $valueType);
+		return new ArrayType($itemType->toArrayKey(), $valueType);
 	}
 
 	public function flipArray(): Type
diff --git a/src/Type/MixedType.php b/src/Type/MixedType.php
index 9b07022d5e..4633760d19 100644
--- a/src/Type/MixedType.php
+++ b/src/Type/MixedType.php
@@ -223,7 +223,7 @@ public function fillKeysArray(Type $valueType): Type
 			return new ErrorType();
 		}
 
-		return new ArrayType($this->getIterableValueType(), $valueType);
+		return new ArrayType($this->getIterableValueType()->toArrayKey(), $valueType);
 	}
 
 	public function flipArray(): Type
diff --git a/src/Type/Php/ArrayCombineHelper.php b/src/Type/Php/ArrayCombineHelper.php
index b8bb3f445a..d4744cfe02 100644
--- a/src/Type/Php/ArrayCombineHelper.php
+++ b/src/Type/Php/ArrayCombineHelper.php
@@ -98,9 +98,9 @@ public function getReturnAndThrowType(Expr $firstArg, Expr $secondArg, Scope $sc
 					return [new NeverType(), TrinaryLogic::createNo()];
 				}
 
-				$keyType = $itemType->toString();
+				$keyType = $itemType->toString()->toArrayKey();
 			} else {
-				$keyType = $itemType;
+				$keyType = $itemType->toArrayKey();
 			}
 		} else {
 			$keyType = new MixedType();
diff --git a/tests/PHPStan/Analyser/nsrt/array-combine-php8.php b/tests/PHPStan/Analyser/nsrt/array-combine-php8.php
index 1a1a78c411..76da9400e5 100644
--- a/tests/PHPStan/Analyser/nsrt/array-combine-php8.php
+++ b/tests/PHPStan/Analyser/nsrt/array-combine-php8.php
@@ -110,7 +110,7 @@ function withUnionConstArraysDifferentArraysCount(): void
 		}
 	}
 
-	assertType("non-empty-array<1|'2'|'3', 'apple'|'avocado'|'banana'|'pear'>", array_combine($a, $b));
+	assertType("non-empty-array<1|2|3, 'apple'|'avocado'|'banana'|'pear'>", array_combine($a, $b));
 }
 
 function withUnionConstArraysAndDifferentFiniteKeysCount(bool $bool): void
@@ -123,7 +123,7 @@ function withUnionConstArraysAndDifferentFiniteKeysCount(bool $bool): void
 		$b = ['apple', 'banana'];
 	}
 
-	assertType("non-empty-array<''|'1'|'2', 'apple'|'avocado'|'banana'>", array_combine($a, $b));
+	assertType("non-empty-array<1|2|'', 'apple'|'avocado'|'banana'>", array_combine($a, $b));
 }
 
 /**
diff --git a/tests/PHPStan/Analyser/nsrt/array-fill-keys-php8.php b/tests/PHPStan/Analyser/nsrt/array-fill-keys-php8.php
index 4710482534..07c06367dc 100644
--- a/tests/PHPStan/Analyser/nsrt/array-fill-keys-php8.php
+++ b/tests/PHPStan/Analyser/nsrt/array-fill-keys-php8.php
@@ -7,7 +7,7 @@
 function mixedAndSubtractedArray($mixed): void
 {
 	if (is_array($mixed)) {
-		assertType("array<mixed, 'b'>", array_fill_keys($mixed, 'b'));
+		assertType("array<'b'>", array_fill_keys($mixed, 'b'));
 	} else {
 		assertType("*NEVER*", array_fill_keys($mixed, 'b'));
 	}
diff --git a/tests/PHPStan/Analyser/nsrt/array-fill-keys.php b/tests/PHPStan/Analyser/nsrt/array-fill-keys.php
index 231b2dcbe5..eabf069c86 100644
--- a/tests/PHPStan/Analyser/nsrt/array-fill-keys.php
+++ b/tests/PHPStan/Analyser/nsrt/array-fill-keys.php
@@ -91,17 +91,17 @@ function withNotConstantArray(array $foo, array $bar, array $baz, array $floats,
 	assertType("array<string, null>", array_fill_keys($foo, null));
 	assertType("array<int, null>", array_fill_keys($bar, null));
 	assertType("array<'foo', null>", array_fill_keys($baz, null));
-	assertType("array<numeric-string&uppercase-string, null>", array_fill_keys($floats, null));
-	assertType("array<bool|int|string, null>", array_fill_keys($mixed, null));
+	assertType("array<int|(numeric-string&uppercase-string), null>", array_fill_keys($floats, null));
+	assertType("array<int|string, null>", array_fill_keys($mixed, null));
 	assertType('array<string, null>', array_fill_keys($list, null));
 	assertType('*ERROR*', array_fill_keys($objectsWithoutToString, null));
 
 	if (array_key_exists(17, $mixed)) {
-		assertType('non-empty-array<bool|int|string, null>', array_fill_keys($mixed, null));
+		assertType('non-empty-array<int|string, null>', array_fill_keys($mixed, null));
 	}
 
 	if (array_key_exists(17, $mixed) && $mixed[17] === 'foo') {
-		assertType('non-empty-array<bool|int|string, null>', array_fill_keys($mixed, null));
+		assertType('non-empty-array<int|string, null>', array_fill_keys($mixed, null));
 	}
 }
 
diff --git a/tests/PHPStan/Analyser/nsrt/bug-14980.php b/tests/PHPStan/Analyser/nsrt/bug-14980.php
new file mode 100644
index 0000000000..eb62e95e2a
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-14980.php
@@ -0,0 +1,82 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace Bug14980;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param list<int> $ints
+ */
+function decimalIntStringKeys(array $ints): void
+{
+	$keys = [];
+	foreach ($ints as $int) {
+		$keys[] = $int;
+		$keys[] = (string) $int;
+	}
+
+	assertType('list<int|decimal-int-string>', $keys);
+	assertType('array<int, true>', array_fill_keys($keys, true));
+}
+
+/**
+ * @param list<numeric-string> $keys
+ */
+function numericStringKeys(array $keys): void
+{
+	assertType('array<int|numeric-string, true>', array_fill_keys($keys, true));
+}
+
+function fillKeysMixedArray(mixed $m): void
+{
+	if (is_array($m)) {
+		assertType('array<true>', array_fill_keys($m, true));
+	}
+}
+
+/**
+ * @param list<int> $ints
+ */
+function combineDecimalIntStringKeys(array $ints): void
+{
+	$keys = [];
+	foreach ($ints as $int) {
+		$keys[] = $int;
+		$keys[] = (string) $int;
+	}
+
+	assertType('array<int, int|decimal-int-string>', array_combine($keys, $keys));
+}
+
+/**
+ * @param list<numeric-string> $keys
+ * @param list<string> $values
+ */
+function combineNumericStringKeys(array $keys, array $values): void
+{
+	assertType('array<int|numeric-string, string>', array_combine($keys, $values));
+}
+
+class DecimalIntBug
+{
+
+	/** @var array<int, true> */
+	private array $data = [];
+
+	/**
+	 * @param list<int> $ints
+	 */
+	public function set(array $ints): void
+	{
+		$keys = [];
+		foreach ($ints as $int) {
+			$keys[] = $int;
+			$keys[] = (string) $int;
+		}
+
+		$this->data = array_fill_keys($keys, true);
+	}
+
+}