diff --git a/changes.txt b/changes.txt
index 8dec320..49f92ec 100644
--- a/changes.txt
+++ b/changes.txt
@@ -334,6 +334,8 @@ Changes in 1.9 (not yet released)
 
 --------------------------
 Changes in 1.8.6 
+- Makefile now only adds CFLAGS instead of overwriting them.
+- Several spelling fixes (Patch #455). Thanks @J. Puydt
 
 --------------------------
 Changes in 1.8.5 (1st November 2021, svn [r6263])
diff --git a/source/Irrlicht/CD3D9ParallaxMapRenderer.cpp b/source/Irrlicht/CD3D9ParallaxMapRenderer.cpp
index f036fb7..5d002df 100644
--- a/source/Irrlicht/CD3D9ParallaxMapRenderer.cpp
+++ b/source/Irrlicht/CD3D9ParallaxMapRenderer.cpp
@@ -185,12 +185,12 @@ namespace video
 		"mov r0.xy, t0          ; color map  \n"\
 		" \n"\
 		"; original parallax mapping: \n"\
-		"; emulate ps1x _bx2, so substract 0.5f and multiply by 2 \n"\
+		"; emulate ps1x _bx2, so subtract 0.5f and multiply by 2 \n"\
 		"mad r1.xyz, r1, r11, c0; \n"\
 		" \n"\
 		"mul r3, r1.wwww, c6;   ; r3 = (height, height, height) * scale \n"\
 		" \n"\
-		"; emulate ps1x _bx2, so substract 0.5f and multiply by 2 \n"\
+		"; emulate ps1x _bx2, so subtract 0.5f and multiply by 2 \n"\
 		"mad r4.xyz, r4, r11, c0; \n"\
 		" \n"\
 		"mad r2.xy, r3, r4, r0  ; newTexCoord = height * eye + oldTexCoord  \n"\
@@ -205,7 +205,7 @@ namespace video
 		"mov r2.xyz, t2          ; fetch light vector 1 \n"\
 		"mov r3.xyz, t3          ; fetch light vector 2 \n"\
 		" \n"\
-		"; emulate ps1x _bx2, so substract 0.5f and multiply by 2 \n"\
+		"; emulate ps1x _bx2, so subtract 0.5f and multiply by 2 \n"\
 		"mad r1.xyz, r1, r11, c0; \n"\
 		"mad r2.xyz, r2, r11, c0; \n"\
 		"mad r3.xyz, r3, r11, c0; \n"\
diff --git a/source/Irrlicht/COpenGLParallaxMapRenderer.cpp b/source/Irrlicht/COpenGLParallaxMapRenderer.cpp
index 065cea2..d0edb74 100644
--- a/source/Irrlicht/COpenGLParallaxMapRenderer.cpp
+++ b/source/Irrlicht/COpenGLParallaxMapRenderer.cpp
@@ -156,7 +156,7 @@ const char OPENGL_PARALLAX_MAP_PSH[] =
 	"MAD normalMapColor, normalMapColor, {2,2,2,2}, {-1,-1,-1,-1}; \n"\
 	"\n"\
 	"\n"\
-	"# extract eye vector (so substract 0.5f and multiply by 2)\n"\
+	"# extract eye vector (so subtract 0.5f and multiply by 2)\n"\
 	"MAD temp, eyeVector, {2,2,2,2}, {-1,-1,-1,-1};\n"\
 	"\n"\
 	"# height = height * scale \n"\
diff --git a/source/Irrlicht/CXMeshFileLoader.cpp b/source/Irrlicht/CXMeshFileLoader.cpp
index feddb40..30a043e 100644
--- a/source/Irrlicht/CXMeshFileLoader.cpp
+++ b/source/Irrlicht/CXMeshFileLoader.cpp
@@ -1116,7 +1116,7 @@ bool CXMeshFileLoader::parseDataObjectSkinWeights(SXMesh &mesh)
 
 	if (!getNextTokenAsString(TransformNodeName))
 	{
-		os::Printer::log("Unknown syntax while reading transfrom node name string in .x file", ELL_WARNING);
+		os::Printer::log("Unknown syntax while reading transform node name string in .x file", ELL_WARNING);
 		os::Printer::log("Line", core::stringc(Line).c_str(), ELL_WARNING);
 		return false;
 	}
diff --git a/source/Irrlicht/Makefile b/source/Irrlicht/Makefile
index 4a870dc..0208c01 100644
--- a/source/Irrlicht/Makefile
+++ b/source/Irrlicht/Makefile
@@ -85,7 +85,7 @@ endif
 ifdef PROFILE
 CPPFLAGS += -pg
 endif
-CFLAGS := -DPNG_THREAD_UNSAFE_OK -DPNG_NO_MMX_CODE -DPNG_NO_MNG_FEATURES -DPNG_ARM_NEON_OPT=0
+CFLAGS += -DPNG_THREAD_UNSAFE_OK -DPNG_NO_MMX_CODE -DPNG_NO_MNG_FEATURES -DPNG_ARM_NEON_OPT=0
 
 sharedlib sharedlib_osx: CPPFLAGS += -fPIC
 # TODO: also necessary on sharedlib_osx?