diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8547ab87..936e9ffd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.10)
+cmake_minimum_required(VERSION 3.13)
 
 # Extract version from miniaudio.h
 file(READ "${CMAKE_CURRENT_SOURCE_DIR}/miniaudio.h" MINIAUDIO_HEADER_CONTENTS)
@@ -660,6 +660,18 @@ if (UNIX)
     endif()
 endif()
 
+# APPLE is true for all Apple platforms. 
+# For macOS (MA_APPLE_DESKTOP, "Darwin" in CMake), the code uses CoreAudio that does not need Objective-C.
+# For the other Apple platforms, the code uses AVFoundation that requires Objective-C.
+if(APPLE AND NOT (CMAKE_SYSTEM_NAME STREQUAL "Darwin"))
+    if(MINIAUDIO_FORCE_CXX)
+        enable_language(OBJCXX)
+        set_source_files_properties(miniaudio.c PROPERTIES LANGUAGE OBJCXX)
+    else()
+        enable_language(OBJC)
+        set_source_files_properties(miniaudio.c PROPERTIES LANGUAGE OBJC)
+    endif()
+endif()
 
 # Static Libraries
 add_library(miniaudio
diff --git a/miniaudio.h b/miniaudio.h
index 1e50096f..00f0cb04 100644
--- a/miniaudio.h
+++ b/miniaudio.h
@@ -56092,7 +56092,6 @@ static MA_INLINE void ma_lpf1_process_pcm_frame_f32(ma_lpf1* pLPF, float* pY, co
     ma_uint32 c;
     const ma_uint32 channels = pLPF->channels;
     const float a = pLPF->a.f32;
-    const float b = 1 - a;
 
     MA_ASSUME(channels > 0);
     for (c = 0; c < channels; c += 1) {
@@ -56100,9 +56099,9 @@ static MA_INLINE void ma_lpf1_process_pcm_frame_f32(ma_lpf1* pLPF, float* pY, co
         float x  = pX[c];
         float y;
 
-        y = b*x + a*r1;
+        y = x + a*(r1 - x);
 
-        pY[c]           = y;
+        pY[c]            = y;
         pLPF->pR1[c].f32 = y;
     }
 }
@@ -56964,8 +56963,7 @@ static MA_INLINE void ma_hpf1_process_pcm_frame_f32(ma_hpf1* pHPF, float* pY, co
 {
     ma_uint32 c;
     const ma_uint32 channels = pHPF->channels;
-    const float a = 1 - pHPF->a.f32;
-    const float b = 1 - a;
+    const float b = pHPF->a.f32;
 
     MA_ASSUME(channels > 0);
     for (c = 0; c < channels; c += 1) {
@@ -56973,7 +56971,7 @@ static MA_INLINE void ma_hpf1_process_pcm_frame_f32(ma_hpf1* pHPF, float* pY, co
         float x  = pX[c];
         float y;
 
-        y = b*x - a*r1;
+        y = b*(x + r1) - r1;
 
         pY[c]            = y;
         pHPF->pR1[c].f32 = y;