diff -Naur a/Makefile b/Makefile
--- a/Makefile	2022-06-10 04:51:46.000000000 +0300
+++ b/Makefile	2022-08-01 10:28:52.698923925 +0300
@@ -27,6 +27,7 @@
 DESTDIR=
 LIBDIR_NAME=lib
 SHAREDLIB_DIR=$(PREFIX)/lib
+INCLUDES_DIR=$(PREFIX)/include
 PROJECT_NAME=openh264
 MODULE_NAME=gmpopenh264
 GMP_API_BRANCH=Firefox39
@@ -286,14 +287,14 @@
 endif
 
 $(PROJECT_NAME).pc: $(PROJECT_NAME).pc.in
-	@sed -e 's;@prefix@;$(PREFIX);' -e 's;@libdir@;$(PREFIX)/lib;' -e 's;@VERSION@;$(FULL_VERSION);' -e 's;@LIBS@;;' -e 's;@LIBS_PRIVATE@;$(STATIC_LDFLAGS);' < $< > $@
+	@sed -e 's;@prefix@;$(PREFIX);' -e 's;@libdir@;$(SHAREDLIB_DIR);' -e 's;@includesdir@;$(INCLUDES_DIR);' -e 's;@VERSION@;$(FULL_VERSION);' -e 's;@LIBS@;;' -e 's;@LIBS_PRIVATE@;$(STATIC_LDFLAGS);' < $< > $@
 
 $(PROJECT_NAME)-static.pc: $(PROJECT_NAME).pc.in
-	@sed -e 's;@prefix@;$(PREFIX);' -e 's;@libdir@;$(PREFIX)/lib;' -e 's;@VERSION@;$(FULL_VERSION);' -e 's;@LIBS@;$(STATIC_LDFLAGS);' -e 's;@LIBS_PRIVATE@;;' < $< > $@
+	@sed -e 's;@prefix@;$(PREFIX);' -e 's;@libdir@;$(SHAREDLIB_DIR);' -e 's;@includesdir@;$(INCLUDES_DIR);' -e 's;@VERSION@;$(FULL_VERSION);' -e 's;@LIBS@;$(STATIC_LDFLAGS);' -e 's;@LIBS_PRIVATE@;;' < $< > $@
 
 install-headers:
-	mkdir -p $(DESTDIR)$(PREFIX)/include/wels
-	install -m 644 $(SRC_PATH)/codec/api/wels/codec*.h $(DESTDIR)$(PREFIX)/include/wels
+	mkdir -p $(DESTDIR)$(INCLUDES_DIR)/wels
+	install -m 644 $(SRC_PATH)/codec/api/wels/codec*.h $(DESTDIR)$(INCLUDES_DIR)/wels
 
 install-static-lib: $(LIBPREFIX)$(PROJECT_NAME).$(LIBSUFFIX) install-headers
 	mkdir -p $(DESTDIR)$(PREFIX)/$(LIBDIR_NAME)
diff -Naur a/openh264.pc.in b/openh264.pc.in
--- a/openh264.pc.in	2022-06-10 04:51:46.000000000 +0300
+++ b/openh264.pc.in	2022-08-01 10:38:28.231850059 +0300
@@ -1,6 +1,6 @@
 prefix=@prefix@
 libdir=@libdir@
-includedir=${prefix}/include
+includedir=@includesdir@
 
 Name: OpenH264
 Description: OpenH264 is a codec library which supports H.264 encoding and decoding. It is suitable for use in real time applications such as WebRTC.