diff --git a/app-common/src/main/java/im/angry/openeuicc/core/EuiccChannelManager.kt b/app-common/src/main/java/im/angry/openeuicc/core/EuiccChannelManager.kt
index aaf1659..ab3914c 100644
--- a/app-common/src/main/java/im/angry/openeuicc/core/EuiccChannelManager.kt
+++ b/app-common/src/main/java/im/angry/openeuicc/core/EuiccChannelManager.kt
@@ -81,10 +81,12 @@ open class EuiccChannelManager(protected val context: Context) {
             var euiccChannel: EuiccChannel? = tryOpenEuiccChannelPrivileged(uiccInfo, channelInfo)
 
             if (euiccChannel == null) {
+                Log.i(TAG, "Trying OMAPI for slot ${uiccInfo.slotIndex}")
                 try {
                     euiccChannel = OmapiChannel(seService!!, channelInfo)
                 } catch (e: IllegalArgumentException) {
                     // Failed
+                    Log.w(TAG, "OMAPI APDU interface unavailable for slot ${uiccInfo.slotIndex}.")
                 }
             }
 
diff --git a/app/src/main/java/im/angry/openeuicc/core/PrivilegedEuiccChannelManager.kt b/app/src/main/java/im/angry/openeuicc/core/PrivilegedEuiccChannelManager.kt
index e7c19c9..b262e49 100644
--- a/app/src/main/java/im/angry/openeuicc/core/PrivilegedEuiccChannelManager.kt
+++ b/app/src/main/java/im/angry/openeuicc/core/PrivilegedEuiccChannelManager.kt
@@ -13,12 +13,13 @@ class PrivilegedEuiccChannelManager(context: Context): EuiccChannelManager(conte
 
     override fun tryOpenEuiccChannelPrivileged(uiccInfo: UiccCardInfo, channelInfo: EuiccChannelInfo): EuiccChannel? {
         if (uiccInfo.isEuicc && !uiccInfo.isRemovable) {
-            Log.d(TAG, "Using TelephonyManager for slot ${uiccInfo.slotIndex}")
+            Log.i(TAG, "Trying TelephonyManager for slot ${uiccInfo.slotIndex}")
             // TODO: On Tiramisu, we should also connect all available "ports" for MEP support
             try {
                 return TelephonyManagerChannel(channelInfo, tm)
             } catch (e: IllegalArgumentException) {
                 // Failed
+                Log.w(TAG, "TelephonyManager APDU interface unavailable for slot ${uiccInfo.slotIndex}, falling back")
             }
         }
         return null
diff --git a/libs/lpac-jni/build.gradle b/libs/lpac-jni/build.gradle
index f3c9d40..9faf136 100644
--- a/libs/lpac-jni/build.gradle
+++ b/libs/lpac-jni/build.gradle
@@ -12,6 +12,12 @@ android {
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         consumerProguardFiles "consumer-rules.pro"
+
+        externalNativeBuild {
+            ndkBuild {
+                arguments '-j4'
+            }
+        }
     }
 
     buildTypes {
diff --git a/libs/lpac-jni/src/main/jni/Android.mk b/libs/lpac-jni/src/main/jni/Android.mk
index 08d7de6..e307295 100644
--- a/libs/lpac-jni/src/main/jni/Android.mk
+++ b/libs/lpac-jni/src/main/jni/Android.mk
@@ -1,14 +1,29 @@
 LOCAL_PATH := $(call my-dir)
 
 # function to find all *.c files under a directory
+# Detecting the operating system
+ifeq ($(OS),Windows_NT)
+# Windows-specific commands
 define all-c-files-under
-$(patsubst ./%,%, \
-  $(shell cd $(LOCAL_PATH) ; \
-          find $(1) -name "*.c" -and -not -name ".*" -maxdepth 1) \
- )
+  $(patsubst .\%,%, \
+    $(shell cd $(LOCAL_PATH) & \
+            dir /b/s $(subst /,\,$(1))\*.c) \
+   )
 endef
+else
+# UNIX commands
+define all-c-files-under
+  $(patsubst ./%,%, \
+    $(shell cd $(LOCAL_PATH) ; \
+            find $(1) -name "*.c" -and -not -name ".*" -maxdepth 1) \
+   )
+endef
+endif
 
 include $(CLEAR_VARS)
+LOCAL_SHORT_COMMANDS := true
+APP_SHORT_COMMANDS := true
+
 # libcjson
 LOCAL_MODULE := lpac-cjson
 LOCAL_SRC_FILES := \
@@ -16,6 +31,9 @@ LOCAL_SRC_FILES := \
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
+LOCAL_SHORT_COMMANDS := true
+APP_SHORT_COMMANDS := true
+
 # libasn1c, the ASN parser component from lpac
 LOCAL_MODULE := lpac-asn1c
 LOCAL_C_INCLUDES := \
@@ -26,6 +44,9 @@ LOCAL_CFLAGS := -DHAVE_CONFIG_H
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
+LOCAL_SHORT_COMMANDS := true
+APP_SHORT_COMMANDS := true
+
 # libeuicc component from lpac, which contains the actual implementation
 LOCAL_MODULE := lpac-euicc
 LOCAL_STATIC_LIBRARIES := lpac-asn1c lpac-cjson
@@ -36,6 +57,9 @@ LOCAL_SRC_FILES := \
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
+LOCAL_SHORT_COMMANDS := true
+APP_SHORT_COMMANDS := true
+
 LOCAL_MODULE := lpac-jni
 LOCAL_STATIC_LIBRARIES := lpac-euicc
 LOCAL_C_INCLUDES := \