diff --git a/mex/build/matlab/configure.ac b/mex/build/matlab/configure.ac
index 9b4bc20bc..91be206aa 100644
--- a/mex/build/matlab/configure.ac
+++ b/mex/build/matlab/configure.ac
@@ -58,6 +58,7 @@ CXXFLAGS="$CXXFLAGS -Wall -Wno-parentheses"
 
 AC_PROG_F77([gfortran g77 f77])
 AC_PROG_CC
+AC_PROG_CC_C99 # mjdgges DLL now uses C99 features (variable declared in for loop)
 AC_PROG_CXX
 AC_PROG_RANLIB
 AX_PROG_LN_S
diff --git a/mex/build/octave/configure.ac b/mex/build/octave/configure.ac
index c523c6a2a..5b0075f0f 100755
--- a/mex/build/octave/configure.ac
+++ b/mex/build/octave/configure.ac
@@ -46,6 +46,7 @@ CXXFLAGS="$CXXFLAGS -Wall -Wno-parentheses"
 
 AC_PROG_F77([gfortran g77 f77])
 AC_PROG_CC
+AC_PROG_CC_C99 # mjdgges DLL now uses C99 features (variable declared in for loop)
 AC_PROG_CXX
 AC_PROG_RANLIB
 AX_PROG_LN_S