diff --git a/src/object.c b/src/object.c
index d2db7963..0950837c 100644
--- a/src/object.c
+++ b/src/object.c
@@ -560,7 +560,7 @@ int getDoubleFromObject(const robj *o, double *target) {
             value = strtod(o->ptr, &eptr);
             if (sdslen(o->ptr) == 0 ||
                 isspace(((const char*)o->ptr)[0]) ||
-                eptr[0] != '\0' ||
+                (size_t)(eptr-(char*)o->ptr) != sdslen(o->ptr) ||
                 (errno == ERANGE &&
                     (value == HUGE_VAL || value == -HUGE_VAL || value == 0)) ||
                 isnan(value))
@@ -602,7 +602,7 @@ int getLongDoubleFromObject(robj *o, long double *target) {
             value = strtold(o->ptr, &eptr);
             if (sdslen(o->ptr) == 0 ||
                 isspace(((const char*)o->ptr)[0]) ||
-                eptr[0] != '\0' ||
+                (size_t)(eptr-(char*)o->ptr) != sdslen(o->ptr) ||
                 (errno == ERANGE &&
                     (value == HUGE_VAL || value == -HUGE_VAL || value == 0)) ||
                 isnan(value))
diff --git a/tests/unit/type/incr.tcl b/tests/unit/type/incr.tcl
index 2287aaae..a58710d3 100644
--- a/tests/unit/type/incr.tcl
+++ b/tests/unit/type/incr.tcl
@@ -144,4 +144,11 @@ start_server {tags {"incr"}} {
         r set foo 1
         roundFloat [r incrbyfloat foo -1.1]
     } {-0.1}
+
+    test {string to double with null terminator} {
+        r set foo 1
+        r setrange foo 2 2
+        catch {r incrbyfloat foo 1} err
+        format $err
+    } {ERR*valid*}
 }