diff --git a/configure.ac b/configure.ac
index c33170a..15ab1db 100644
--- a/configure.ac
+++ b/configure.ac
@@ -140,7 +140,7 @@ esac
 
 # If you're bumping the CK max-version here, you must also bump it in
 # travis/deps.sh otherwise you will break the CI build
-if ! $PKG_CONFIG --exists --atleast-version=0.5.0 --max-version=0.5.1 --print-errors ck ; then
+if ! $PKG_CONFIG --exists --atleast-version=0.5.0 --max-version=0.6.0 --print-errors ck ; then
   AC_MSG_ERROR([ck is required])
 fi
 CFLAGS="$CFLAGS `$PKG_CONFIG --cflags ck`"
@@ -312,7 +312,7 @@ if test -n "$GCC" ; then
     -W -Wundef -Wendif-labels -Wshadow -Wpointer-arith -Wcast-align \
     -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes \
     -Wno-nested-externs -Winline -Wdisabled-optimization \
-    -fstrict-aliasing -pipe -Wno-parentheses"
+    -fstrict-aliasing -pipe -Wno-parentheses -Wno-varargs"
 fi
 AC_SUBST(PC_CFLAGS)
 AC_SUBST(PC_LIBS)
diff --git a/corelib/memory.c b/corelib/memory.c
index 903d15a..c049622 100644
--- a/corelib/memory.c
+++ b/corelib/memory.c
@@ -440,7 +440,6 @@ void *ph_mem_realloc(ph_memtype_t mt, void *ptr, uint64_t size)
 
   hdr = ptr;
   hdr--;
-  ptr = hdr;
 
   if (hdr->mt != mt) {
     memory_panic("ph_mem_realloc: hdr->mt %d != caller provided mt %d %s",
@@ -452,6 +451,7 @@ void *ph_mem_realloc(ph_memtype_t mt, void *ptr, uint64_t size)
     return ptr;
   }
 
+  ptr = hdr;
   hdr = realloc(ptr, size + HEADER_RESERVATION);
   if (!hdr) {
     ph_counter_scope_add(mem_type->scope,
diff --git a/corelib/string.c b/corelib/string.c
index 5df7dc4..af2c074 100644
--- a/corelib/string.c
+++ b/corelib/string.c
@@ -61,6 +61,7 @@ ph_string_t *ph_string_make_slice(ph_string_t *str,
   }
 
   ph_string_init_slice(slice, str, start, len);
+  slice->onstack = false;
   return slice;
 }
 
diff --git a/include/phenom/hashtable.h b/include/phenom/hashtable.h
index 6b05fae..e7b3dd7 100644
--- a/include/phenom/hashtable.h
+++ b/include/phenom/hashtable.h
@@ -17,6 +17,8 @@
 #ifndef PHENOM_HASHTABLE_H
 #define PHENOM_HASHTABLE_H
 
+#include "phenom/defs.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/travis/deps.sh b/travis/deps.sh
index 810c8eb..ba4715c 100755
--- a/travis/deps.sh
+++ b/travis/deps.sh
@@ -10,7 +10,7 @@ esac
 HERE=$PWD
 
 # There is no CK package available for ubuntu yet
-CK_VER=0.5.1
+CK_VER=0.6.0
 CK_RELEASE=https://github.com/concurrencykit/ck/archive/$CK_VER.tar.gz
 if test ! -f $CK_VER.tar.gz ; then
   wget $CK_RELEASE