diff --git a/c/CMakeLists.txt b/c/CMakeLists.txt
index 40b503746e..0d7b315486 100644
--- a/c/CMakeLists.txt
+++ b/c/CMakeLists.txt
@@ -105,14 +105,19 @@ elseif (SASL_IMPL STREQUAL none)
 endif ()
 
 # Set Compiler extra flags for Solaris when using SunStudio
-if(CMAKE_CXX_COMPILER_ID STREQUAL "SunPro" )
-  set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mt" )
+if (CMAKE_CXX_COMPILER_ID STREQUAL "SunPro")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mt -D_REENTRANT")
 endif()
 
-if(CMAKE_C_COMPILER_ID STREQUAL "SunPro" )
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -mt")
+if (CMAKE_C_COMPILER_ID STREQUAL "SunPro")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -mt -D_REENTRANT")
 endif()
 
+# Set linker's extra flags for Solaris (used by SunStudio and GCC without discrimination)
+if (CMAKE_HOST_SOLARIS)
+  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -lsocket")
+endif(CMAKE_HOST_SOLARIS)
+
 # Link in openssl if present
 if (SSL_IMPL STREQUAL openssl)
   set (pn_ssl_impl src/ssl/openssl.c)
@@ -231,9 +236,18 @@ if (CMAKE_COMPILER_IS_GNUCC)
     set (COMPILE_WARNING_FLAGS "${CXX_WARNING_FLAGS}")
   endif (NOT BUILD_WITH_CXX)
 
+  if (CMAKE_HOST_SOLARIS)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D__EXTENSIONS__")
+  endif (CMAKE_HOST_SOLARIS)
+
   if (ENABLE_UNDEFINED_ERROR)
-    set (CATCH_UNDEFINED "-Wl,--no-undefined")
-    set (ALLOW_UNDEFINED "-Wl,--allow-shlib-undefined")
+    if (CMAKE_HOST_SOLARIS)
+      set (CATCH_UNDEFINED "-zdefs")
+      set (ALLOW_UNDEFINED "-znodefs")
+    else(CMAKE_HOST_SOLARIS)
+      set (CATCH_UNDEFINED "-Wl,--no-undefined")
+      set (ALLOW_UNDEFINED "-Wl,--allow-shlib-undefined")
+    endif(CMAKE_HOST_SOLARIS)
   endif (ENABLE_UNDEFINED_ERROR)
 
   if (ENABLE_LINKTIME_OPTIMIZATION)
diff --git a/c/src/reactor/io/posix/io.c b/c/src/reactor/io/posix/io.c
index 5a0de3b10f..949fc8bd89 100644
--- a/c/src/reactor/io/posix/io.c
+++ b/c/src/reactor/io/posix/io.c
@@ -274,7 +274,7 @@ static ssize_t nosigpipe_send(int fd, const void *buffer, size_t size) {
   if (!sigpipeIsPending) {
     sigemptyset(&newSignals);
     sigaddset(&newSignals, SIGPIPE);
-    if (sigmaskErr = pthread_sigmask(SIG_BLOCK, (const sigset_t *)&newSignals, (sigset_t *)&oldSignals))
+    if ((sigmaskErr = pthread_sigmask(SIG_BLOCK, (const sigset_t *)&newSignals, (sigset_t *)&oldSignals)) != 0)
     {
       errno = sigmaskErr;
       return -1;
@@ -288,7 +288,7 @@ static ssize_t nosigpipe_send(int fd, const void *buffer, size_t size) {
       while (-1 == sigtimedwait(&newSignals, NULL, &(struct timespec){ 0, 0 }) && errno == EINTR)
         ; //do nothing
     }
-    if (sigmaskErr = pthread_sigmask(SIG_SETMASK, (const sigset_t *)&oldSignals, (sigset_t *)NULL))
+    if ((sigmaskErr = pthread_sigmask(SIG_SETMASK, (const sigset_t *)&oldSignals, (sigset_t *)NULL)) != 0)
     {
       errno = sigmaskErr;
       return -1;