diff --git a/src/MANYBODY/pair_tersoff.cpp b/src/MANYBODY/pair_tersoff.cpp
index 6be89f9877..caf6f71122 100755
--- a/src/MANYBODY/pair_tersoff.cpp
+++ b/src/MANYBODY/pair_tersoff.cpp
@@ -47,8 +47,7 @@ PairTersoff::PairTersoff(LAMMPS *lmp) : Pair(lmp)
 
   nelements = 0;
   elements = NULL;
-  nparams = 0;
-  maxparam = 0;
+  nparams = maxparam = 0;
   params = NULL;
   elem2param = NULL;
 }
@@ -364,9 +363,9 @@ void PairTersoff::read_file(char *file)
   int params_per_line = 17;
   char **words = new char*[params_per_line+1];
 
-  if (params) delete [] params;
+  if (params) memory->sfree(params);
   params = NULL;
-  nparams = 0;
+  nparams = maxparam = 0;
 
   // open file on proc 0
 
diff --git a/src/input.cpp b/src/input.cpp
index 97eaa5cd58..6fd8e99f66 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -524,7 +524,7 @@ void Input::echo()
 
 void Input::ifthenelse()
 {
-  if (narg < 4) error->all("Illegal if command");
+  if (narg < 3) error->all("Illegal if command");
 
   // substitute for variables in Boolean expression for "if"
   // in case expression was enclosed in quotes
diff --git a/src/variable.cpp b/src/variable.cpp
index 1136593216..fd236b7102 100644
--- a/src/variable.cpp
+++ b/src/variable.cpp
@@ -3163,13 +3163,13 @@ double Variable::evaluate_boolean(char *str)
     // number: push value onto stack
     // ----------------
       
-    } else if (isdigit(onechar) || onechar == '.') {
+    } else if (isdigit(onechar) || onechar == '.' || onechar == '-') {
       if (expect == OP) error->all("Invalid Boolean syntax in if command");
       expect = OP;
       
       // istop = end of number, including scientific notation
       
-      int istart = i;
+      int istart = i++;
       while (isdigit(str[i]) || str[i] == '.') i++;
       if (str[i] == 'e' || str[i] == 'E') {
 	i++;
@@ -3282,7 +3282,7 @@ double Variable::evaluate_boolean(char *str)
       // push current operation onto stack
       
       opstack[nopstack++] = op;
-      
+
     } else error->all("Invalid Boolean syntax in if command");
   }