diff --git a/src/add-ons/kernel/bus_managers/acpi/ACPICAHaiku.cpp b/src/add-ons/kernel/bus_managers/acpi/ACPICAHaiku.cpp
index cf300b8fd2..1587f6bee3 100644
--- a/src/add-ons/kernel/bus_managers/acpi/ACPICAHaiku.cpp
+++ b/src/add-ons/kernel/bus_managers/acpi/ACPICAHaiku.cpp
@@ -1238,7 +1238,8 @@ AcpiOsAcquireGlobalLock(volatile uint32_t *lock)
 		if ((oldValue & ACPI_GLOCK_OWNED) != 0)
 			newValue |= ACPI_GLOCK_PENDING;
 	} while (atomic_test_and_set((int32*)lock, newValue, oldValue) != (int32)oldValue);
-	return (newValue & ACPI_GLOCK_PENDING) != 0;
+
+	return (newValue & ACPI_GLOCK_PENDING) == 0;
 }
 
 
@@ -1259,6 +1260,7 @@ AcpiOsReleaseGlobalLock(volatile uint32_t *lock)
 		oldValue = *lock;
 		newValue = oldValue & ~(ACPI_GLOCK_PENDING | ACPI_GLOCK_OWNED);
 	} while (atomic_test_and_set((int32*)lock, newValue, oldValue) != (int32)oldValue);
+
 	return (oldValue & ACPI_GLOCK_PENDING) != 0;
 }