diff --git a/CMakeLists.txt b/CMakeLists.txt
index 94460d9..5591123 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -69,6 +69,7 @@
 # 2014-08-29 PH converted the file for PCRE2 (which has no C++).
 # 2015-04-24 PH added support for PCRE2_DEBUG
 # 2015-07-16 PH updated for new pcre2_find_bracket source module
+# 2015-08-24 PH correct C_FLAGS setting (patch from Roy Ivy III)
 
 PROJECT(PCRE2 C)
 
@@ -80,7 +81,7 @@ CMAKE_POLICY(SET CMP0026 OLD)
 
 SET(CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake) # for FindReadline.cmake
 
-SET(CMAKE_C_FLAGS -I${PROJECT_SOURCE_DIR}/src)
+SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -I${PROJECT_SOURCE_DIR}/src")
 
 # external packages
 FIND_PACKAGE( BZip2 )
diff --git a/ChangeLog b/ChangeLog
index 0c79904..dcc294d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -154,6 +154,9 @@ non-zero.
 42. Fix two assertion fails in JIT. These issues were found by Karl Skomski
 with a custom LLVM fuzzer.
 
+43. Correct the setting of CMAKE_C_FLAGS in CMakeLists.txt (patch from Roy Ivy 
+III).
+
 
 Version 10.20 30-June-2015
 --------------------------