diff --git a/nifti2/nifti_tool.c b/nifti2/nifti_tool.c
index ac249bf8..4af13d38 100644
--- a/nifti2/nifti_tool.c
+++ b/nifti2/nifti_tool.c
@@ -2284,6 +2284,7 @@ int act_add_exts( nt_opts * opts )
                     opts->etypes.list[ec]);
 
          if( nifti_add_extension(nim, ext, elen, opts->etypes.list[ec]) ){
+            free(edata);   /* may hold the file contents read just above */
             nifti_image_free(nim);
             return 1;
          }
diff --git a/niftilib/nifti1_tool.c b/niftilib/nifti1_tool.c
index 15bb165a..c9344a7f 100644
--- a/niftilib/nifti1_tool.c
+++ b/niftilib/nifti1_tool.c
@@ -1865,6 +1865,7 @@ int act_add_exts( nt_opts * opts )
          }
 
          if( nifti_add_extension(nim, ext, elen, opts->etypes.list[ec]) ){
+            free(edata);   /* may hold the file contents read just above */
             nifti_image_free(nim);
             return 1;
          }